Hi @antgiant ,
I'm using Microsoft Edge - Version 95.0.1020.30 (Official build) (64-bit) to access OWA and cannot get it to turn on Desktop Notifications.
I just tried checking on my end using an Exchange Online account in the same version of Edge, and can reproduce what you enountered:
Then I tested using different browsers like Google Chrome to eliminate whether it is a browser specific issue, and noticed that the issue pesists there.
I've also tried manually adding https://outlook.office.com:443 into the allow notification list of the Edge settings, but still it didn't make any difference:
But when tesing using an outlook.com personal account which also has this option, the toggle can be clicked to turn this on or off successfully:
So based on these test results, seems that it's not a issue with Microsoft Edge, but more likely to be related to the Exchange online side.
By the way, may I know if you have tried turning on desktop notifications in OWA previously? If so, do you have any impression about when was it?