Unable to Highlight Text for Labeling in Azure Foundry Data Training

Question

Unable to Highlight Text for Labeling in Azure Foundry Data Training

thanh.tran quoc 0

I am experiencing a problem in Azure Foundry when adding data for training using the built-in data labeling function. Specifically, I am unable to click and drag to select a word or phrase in the text for labeling... The interface does not allow me to highlight text spans, which prevents me from assigning labels to specific phrases.

2026-03-31_10-33-55

Manish Deshpande 5,665 Reputation points Microsoft External Staff Moderator

2026-04-22T14:01:12.7166667+00:00

Hello thanh.tran quoc

It looks like you’re in the “Add data for training and testing” view (with the Intent dropdown and utterance box) – that interface is for intent/text‐classification scenarios, not span‐level labeling. In a classification project you pick an intent and enter the full utterance, so click‐and‐drag to highlight words or phrases isn’t supported there.

If your goal is to annotate specific text spans (e.g. entities in a sentence), you’ll want to use a Custom NER (Named Entity Recognition) project in Language Studio (sometimes called Azure Language Foundry Tools). That UI gives you two ways to label spans:

• Brush mode – Select the brush icon next to your entity type in the right pane. – Click and drag directly over the text you want to tag.

• Highlight-then-menu mode – Click and drag to highlight a word or phrase in the document. – When the context menu pops up, pick the entity type you’re assigning.

Here’s how to switch over:

Go to https://aka.ms/languageStudio (or your Azure AI Studio URL).

Open or create a project and choose Language → Custom NER.

In the right pane, click “Add entity type” to define at least one entity.

Toggle to the single-document view (top-left) so you see the text editor.

Use either the brush icon or the highlight flow to label spans.

If you truly need text classification (whole-utterance labels), stick with the intent dropdown/utterance box. But for span-level (NER) labeling, move to a Custom NER project.

Let me know if you run into any of these blockers: • You’re already in a Custom NER project but don’t see the brush or menu • You don’t see “Add entity type” in the right pane • Browser or extension issues (browser name + any blockers)
Manish Deshpande 5,665 Reputation points Microsoft External Staff Moderator

2026-04-27T14:22:14.1066667+00:00

Hello

I wanted to check if my last response made sense. I’d be glad to assist further or explain anything in more detail and please accept as Yes and upvote if the answer is helpful so that it can help others in the community.

1 answer

Your answer

Manish Deshpande 5,665 Reputation points Microsoft External Staff Moderator

2026-04-22T14:01:12.7166667+00:00

Hello thanh.tran quoc

It looks like you’re in the “Add data for training and testing” view (with the Intent dropdown and utterance box) – that interface is for intent/text‐classification scenarios, not span‐level labeling. In a classification project you pick an intent and enter the full utterance, so click‐and‐drag to highlight words or phrases isn’t supported there.

If your goal is to annotate specific text spans (e.g. entities in a sentence), you’ll want to use a Custom NER (Named Entity Recognition) project in Language Studio (sometimes called Azure Language Foundry Tools). That UI gives you two ways to label spans:

• Brush mode – Select the brush icon next to your entity type in the right pane. – Click and drag directly over the text you want to tag.

• Highlight-then-menu mode – Click and drag to highlight a word or phrase in the document. – When the context menu pops up, pick the entity type you’re assigning.

Here’s how to switch over:

Go to https://aka.ms/languageStudio (or your Azure AI Studio URL).

Open or create a project and choose Language → Custom NER.

In the right pane, click “Add entity type” to define at least one entity.

Toggle to the single-document view (top-left) so you see the text editor.

Use either the brush icon or the highlight flow to label spans.

If you truly need text classification (whole-utterance labels), stick with the intent dropdown/utterance box. But for span-level (NER) labeling, move to a Custom NER project.

Let me know if you run into any of these blockers: • You’re already in a Custom NER project but don’t see the brush or menu • You don’t see “Add entity type” in the right pane • Browser or extension issues (browser name + any blockers)
Manish Deshpande 5,665 Reputation points Microsoft External Staff Moderator

2026-04-27T14:22:14.1066667+00:00

Hello

I wanted to check if my last response made sense. I’d be glad to assist further or explain anything in more detail and please accept as Yes and upvote if the answer is helpful so that it can help others in the community.

Answer 1

Hello thanh.tran quoc,

Greetings!

Thanks for raising this question in Q&A forum.

This is a known usability issue that a few users have run into. The most common reasons why text highlighting doesn't work in the Azure Foundry data labeling interface are: no entity type is selected before trying to highlight, a browser compatibility issue, a CORS misconfiguration on the storage account, or missing storage permissions. Let me walk you through the steps to fix this.

Step 1: Make sure you select an entity type first

This is the most commonly missed step. In the right side pane, you must first add an entity type to your project before you can start labeling your data. You cannot highlight text until at least one entity type is added and selected. So go to the right-hand pane, add your entity (e.g., "ProductName", "Date", etc.), click on it to select it, and then try to click and drag to highlight text.

Step 2: Switch to single document view

Change to a single document view from the left side in the top menu, or select a specific document to start labeling. Text selection only works when you are viewing one document at a time, not in the document list view.

Step 3: Use Microsoft Edge browser

The labeling interface works best on Microsoft Edge. If you are using another browser like Chrome or Firefox, please switch to Edge and try again, as some drag-select interactions can behave unexpectedly on other browsers.

Step 4: Check CORS settings on your storage account

A misconfigured storage account can cause the labeling UI to not respond properly. Make sure to allow GET, PUT, and DELETE methods when enabling Cross-Origin Resource Sharing (CORS). Set allowed origins to https://language.cognitive.azure.com, allow all headers by adding * to the allowed header values, and set the maximum age to 500.

Step 5: Verify your storage role permissions

Make sure that the user making changes has the Storage Blob Data Contributor role assigned to them. Without this role, the labeling interface may load but not function correctly. You can set this from the Azure portal under your Storage Account > Access Control (IAM).

Step 6: Try the autolabeling feature as an alternative

If manual highlighting still doesn't work, you can use the autolabeling feature to ensure complete labeling as a temporary workaround while the issue is investigated.

Step 7: Report it if the issue persists

If none of the above steps resolve it, this may be a portal bug. Please raise a support ticket from the Azure portal so the engineering team can look into it directly.

If this answer helps you kindly accept the answer which will help others who have similar questions.

Best Regards,

Jerald Felix.

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Unable to Highlight Text for Labeling in Azure Foundry Data Training

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