I'll have to be a "me too" on the issue of taskbar showing the wrong apps when you hover over the button (current version and at least the previous one).
I have Start11 installed on three machines.
It occurs on a machine with one monitor (most of the time, occasionally switch to expand to include TV)
On my machine with three monitors (work) the taskbar will become 90% unresponsive eventually.
In both case I can go to taskbar>right click>configure start11>taskbar > Restart Explorer to reset it to working (for a while).
Third machine is a laptop that I don't use often enough to tell if there's an issue.
I ended up simply turning off Taskbar enhancements in Start11. I really got it for the actual Start Menu anyway (which works fine (no idea what MS was thinking with the Win11 menu)). Though I do like the "sometimes combined" settings when it works.