I have the same problem too.
Fences 18.104.22.168 + Windows11 22H2 OS22621.675
And, I already tried purge and reinstalled and reboot, however, the problem still exists.
After installing and starting Fences4, moving the mouse cursor to the icon of Excel and other software(example Chrome) will show the preview window, but after selecting one of them and opening it, then moving the cursor to the icon of Excel and other software(example Chrome), the preview window will not be shown again.
You can only move the cursor at first, and click on other software, and then return to click on Excel to resume normal. (But the problem will reappear again in a short while)
For comparison, if disable or uninstall Fences, this problem does not occur again.
Here is a screen recording of the problem, I hope it will help you understand：
Please guide me how to fix this problem, thanks!