Ability Icons Disappearing after reload

Hello everyone, I have been having a problem with disappearing ability icons for a long time. First I thought it was a buggy module, but than I tried it in a fresh world without modules and the problem still persists.
The problem: I create a new ability, choose a cool icon from the Core Data folder and sometimes the icon just dissapears after a page refresh(F5 reload) and the standard “white bag” icon is there instead. I had this problem for months and I finally found one way to replicate it: it happens everytime with recharge abilities. If you click on the ability icon to use it as an action and reload your page afterwards its icon gets replaced by the standard icon. I really don’t understand why and it is making me crazy.
It’s not only with recharge abilities but with some other spells and abilities. I wasn’t able to reproduce the bug with those things unfortunately. It also only happens with actors on a map and not in the sidebar or compendiums.
Hopefully someone can help me with this problem, its minor but annoying. ^^
Here are some pictures if my broken english is hard to understand xd

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