FWIW, I see this problem as well and I was coming to post something about it when I saw this thread. I am on the 22H2 build (OS build 22621.1848) as far as Windows is concerned. My symptoms match the OP's exactly - especially the part about it seeming random in that it will work sometimes and then stop working without any notice. Basically when the problem happens, you can hover over the taskbar icons but nothing pops up. It is still possible to click on it; however, it will only display the most recent item (if stacked). To fix this, I have gotten used to keeping my Task Manager open so that I can use the 'Restart Task' on Windows Explorer which ALWAYS fixes the problem, but it's also inevitable that it will happen again but seems random as to when.
Now, I had gone back through some old release notes/forum posts and saw that this problem had apparently been corrected some time ago but I never really found that to be the case. So, I started thinking about what kinds of things might be unique to my setup that might cause this problem and I came up with 2 things that might be worth mentioning. The first is that I currently use a KVM switch which allows me to toggle between using the same keyboard and mouse on 2 different systems (in this case, my home PC and my work laptop) but everything goes through the same monitor. From what I can tell, switching from my home PC to my work laptop causes it to lose focus in terms of system processing (Windows makes the disconnect and reconnect sound for example) but when I switch back to my home PC, it normally still works fine (although I do notice that it seems to first need to resize itself automatically) but at some point, I will lose the ability to peak/preview as called out by the OP. The second thing that might be unique to my system is that I have my graphics card connected via HDMI to a 4K TV in addition to my computer monitor (via DisplayPort), which is 1080p. As such, I do need to switch resolutions a few times or engage HDR mode which does cause my monitor to refresh itself each time but I have not noticed anything happening with those actions to suggest that this could be the culprit; I just thought I would mention it as well.
I have tried uninstalling, restarting, and then reinstalling Start11 1.45 and it seems like that will allow it to work longer than it would if I was just restarting the task in the Task Manager but you can definitely count on it still happening.