Sorry, but if something works for you, that doesn't mean it always works for everyone with their own circumstances, especially on a highly modded server with tons of plugins. I believe the most advanced user here knows how to resolve that, if just by reloading the image library. They must be putting in a lot more work than that if that is the case.

I put all my images on IMGUR, and most of them work, but some don't. That happened a month ago. It used to work just fine.

This is just a way around it to get things fixed for them and some of my private plugins.

That's why some paid plugins are now moving their images. Hoster to somewhere else or Discord.

Thats why most paid plugins are now moving their image Hoster

I run a highly modded server (102) and ALL my plugins that use image files are all on imgur , i dont know of any plugin that uses another host , an example would be helpful.
If server owners are having trouble with one image (from the dev) they should try another and see if that works. 
Thats about it for me on this subject. hope you resolve your problems.

102 is quite a lot but mine is doubled. and the answer still the same as above.