How to fix outlook in office 365 "we're having trouble fetching results from the server"

Hi,

I was trying to use search bar in my outlook today, and it gives me this "we're having trouble fetching results from the server" message. So I tried reboot outlook, and reboot my PC, it is still having this problem.

So I decide to use the web version of outlook in office 365. It still has this issue. I think this is related to the Microsoft server and not my computer. Caused the office 365 is just running at Chrome.

Then I tried to use my iphone based outlook, funny thing is the search result only comes back from the sent box, the inbox has no result back at all.

Can anyone help with this issue?