These are very odd, and possibly very specific issues, but I had the following problems when I upgraded to Win 11.
iCue - I run the Corsair iCue software on my machine to basically swtich off all of the RGB lights on my fans, ram, AIO Cooler and Keyboard. When I upgraded, iCue lost sight of all of my connected devices, and my whole rig lit up like a flashing Christmas tree. To resolve I had to uninstall the software, re-start my machine, and re-instal the software and set everything up again.
Excel - A strange one, but after the upgrade I could no longer double click on an excel file to open it up. It would open up the excel application, but only show a blank grey screen. I had to open the excel application first, and then Open my excel within the application itself to get it to open my files. A bit annoying. I haven't actually resolved this one yet.
USB / Bluetooth Devices - 1 USB device, and my bluetooth headphones where not showing up after the upgrade. I had to go to my Device Manager settings to get my machine to recognise them again.
Other wierd things I've noticed, and have mostly resolved
- It stopped showing the date in the bottom right corner of my monitors., it only showed the time, and I had to click on it to see what date it was. I like to know the date, so I fixed this in settings somewhere.
- There was an app history or "apps you have used recently" menu beside my start button when I upgraded. I really wasn't a fan, so I got rid of that in settings.
- The Notifications pop up or tab in the right hand corner is a pain. It's basically just notifications from Nvidia repeatedly telling me to update.
- I find that applications are no longer in focus when I interact with them., their default seems to be to go to the background. For example, if I can take a screenshot with the Snipping Tool, I then have to click on the app's icon in my toolbar to see the screenshot I just took. Before this would persist in the foreground. I haven't resolved this one yet.
- I had to reconfigured my headphones, mic, and all that. I have speakers plugged into my PC, and speakers in my monitor, that I don't like to use, so I disable these in settings. I had to redo all of this when I upgraded. I do find though that I'm not really a fan of using the new settings menu for all of this, - like configuring my headphones and mic - but thankfully Windows still supports all of the old menu's that I'm more familiar with for configuring all of this stuff.
So yeah, these are very nuanced issues I've had, and they're probably specific to me, But thought I'd share.
Overall I'm happy enough with Win 11 so far, and I'm glad I bit the bullet and made the move.