Loading category image
On my test system, which I installed just yesterday, I find that after creating a new category, the Image button does not respond when clicked. I have to navigate away from the category page, then come back to it before I can click on that button to load a custom image for the category. Happens all the time.
Also, after deleting a category image and loading a new one in its place, I observed that if I navigate away from that page and then come back to it, the old image is the one that's showing, instead of the mew one.
https://github.com/designcreateplay/NodeBB/commit/26673d3ada9e0be42e35a802cb2952ba133dc2a5 Should fix the image button not responding.
As for image coming back after you upload an image it is not actually saved. You have to click save at the bottom of the page.