I've got the same issue. Windows 11, up-to-date including optional updates, Laptop DELL is updated as well.
I install Lightshot with administrative permissions and it doesn't install properly: I can't see it in systray, prtscr doesn't work, though I can see it in the processes. I end the process, run the app as Admin and it doesn't help... Snipping tool is switched off. Guys, any help is very much appreciated :)