I am not sure the cause of the issue, but for some reason despite being on the same Wifi (MusicBee is updated to 3.6, I'm on Windows 10 and Android 12) I am able to sync when wired but of course that doesn't have the back-sync for playcounts which is why I'm using the app) I have been unable to sync today. It's been a couple of weeks since I last did, so I worried that Android had messed with the permissions (I have since disabled the option that lets them do this). I tried re-installing the app, clearing app cache, clearing app storage, I've I tried multiple wired syncs, but currently I'm stuck on the screen where it says "you have to run a wired sync first". Running one doesn't change anything, locating server immediately says not found without it seeming like it's attempting a search at all.
Is the MusicBee version 3.6.9202 OK?
Did you download it from the website? From the store? Is it portable?
Is the app version 2.8.1?
Here, the results of debugging on Android 12 show that reverse sync of play counts worked successfully with both GoneMad and Poweramp, so I think it's an environmental issue.
Is the model name of your device( under Settings → About Phone (or Device)) listed in the MusicBee device list?
If it's not there, you still need to use wired sync.
If it is there, please check that the network connection is working properly, such as by checking the Windows Firewall.
Additionally, clearing the cache or storage is generally not necessary. Doing this alone can cause issues such as old data being retrieved during reverse sync.