It is a known limitation, and it is indeed not listed in the FAQ or the documentation. Currently there's no fix for it, only workarounds, such as enabling "Decombine: Active group" and having the group active while moving the mouse to the other side.

You're using StartIsBack/StartAllBack, right?
See the discussion here:

https://rammichael.com/7-taskbar-tweaker-on-windows-11-with-windows-10s-taskbar#comment-13026

Is it related to the taskbar or to the tweaker's options? The z-order is not something the tweaker controls, especially not with the main window which is mostly standard. Sounds like the problem is with your system, unless I misunderstood what you mean.

OK, so I'm closing it. If it happens again, please try to explain in a way that is easier to understand, maybe with a help of a video or screenshots.

Fixed in v5.12.

Unless you meant something else, there's a registry option for that:

https://www.tenforums.com/tutorials/104754-change-width-taskbar-buttons-windows.html

Sorry, I don't quite follow. Did you solve your issue?

Another example of what?

Should be fixed in v5.11.3.2 beta.

You can access the advanced options from the main window context menu or from the tray icon context menu.