Let me start by saying this is my first attempt at modding anything ever, that being said, no matter what i do i can't get the thumbnail (and map) to update on the world editor.
When i double click on the cell, the cell is fine, everything is as i updated it, but no matter what i do the thumbnail stays the same, im probably not doing something obvious because i can't find this problem anywhere else.
In the images you can see how to thumbnail stays blank (if i open the file again) or it stays with the very first version i used. The cell however is as it should be.