Addon Installation Problerm

Still haven’t found the solution to this problem. When I try to install a randin addon in Blender 2.91 via the usual method, Blender immediately confirms that it loaded the add-on successfully via the blue tag that appears at the bottom of the screen. Tthe un-zipped addon also appears in
“Roaming>Blender>Foundation>Blender>2.91>scripts>addons>xxxxxxx”
Yet, it may take a few minutes until I see the activate tick box ---- if I see it at all. Windows 10 Pro and all software drivers are up to date. I’ve uninstalled then reinstalled Blender 2.91 several times. No error message appears.

I had the same for a few weeks, and noticed that I had to give a little scroll on my mouse (just one tick) and pop, there appears the addon.

I tried your suggestion, but it does not appear to work for me.