A Microsoft file hosting and synchronization service.
Hi Richard,
If you can open the files directly in OneDrive but cannot find them when attaching an email, the files are likely not fully available through File Explorer or Outlook’s attachment picker.
First, make sure OneDrive is signed in and syncing. Then open File Explorer > OneDrive, right-click the folder containing your files and select “Always keep on this device.” This downloads the files locally so Outlook can access them normally.
In Outlook, you can also select Attach File > OneDrive and choose the file directly, rather than browsing the local folders.
I would try these steps before resetting Microsoft 365, since a full reset is unlikely to be necessary.
Thank you, and feel free to respond back for more assistance.