The provided ASIO output plug-in & possibly the WASAPI output plug-in for some may not be working - this still needs to be investigated to replicate & then resolve where possible.
The shuffle table may not act as expected & is still to be finished being re-worked. This was also present in the 216xx builds & possibly 215xx.
SNSF sets won't play correctly or at all which is still to be investigated fully.
Smart App Control with Windows 11 can either cause the first run after an install to take an age or it'll just randomly block dlls from being loaded (e.g. image.w5s) which depending on what's blocked will either prevent WACUP from being able to complete loading or it'll be somewhat hobbled often until restarting & then everything will usually be allowed to load. I don't like this!
The re-used ml_pmp (portables) plug-in from the 5.666 installer can & will fail due to runtime conflicts which mean it'll most likely be blocked from being used under wacup in near term.