Not a problem I've seen reported before. I just ran it for a few minutes that way, and didn't find it 'buggy', nor did it crash.
You should post your logs. Even if the logs don't seem to show anything about the exact problem, they still reveal a lot about your configuration which might give someone an idea.
The usual suggestion here would be to update your video card driver; also, what video card is it?
server: NextPVR 5.0.7/Win10 2004/64-bit/AMD A6-7400k/hvr-2250 & hvr-1250/Winegard Flatwave antenna/Schedules Direct main client: NextPVR 5.0.7 Desktop Client; LG 50UH5500 WebOS 3.0 TV
When "stay on top" enabled, changing channels is slower (1sec pause).
If it fails to change channels, it pauses, and I have to stop it, then live tv, to resume.
If it completely fails, I have to close NPVR using windows force close.
Whereas, with "stay on top" disabled, change channels is quick, and doesn't crash/hang.
This so repeatable, I think I won't bother enabling "stay on top".
There is no reason it would be any different. If you can reproduce the problem and post the logs, I check out why. For comparison's sake, post logs showing a few channel changes with it enabled, and a few channel changes with it disabled.