Hello. I can't seem to reproduce the Ampersand bug you found. Can you please share an example image on your wiki that was causing the problem?
For my demo page I basically cut and pasted this tabber:
4e = [[Image:4e orc.jpg|250px|Orcs]]|-|
3e = [[File:Orc.JPG|250px]]|-|
2e = [[File:Monster_Manual_-_2D&D_-_Orc_-_p281.png|250px]]|-|
1e = [[File:Monster_Manual_-_1D&D_-_Orc_-_p76.png|250px]]
and then converted it to a Gallery (and removed the File: tags). Then noticed that the last two images did not show up. Here are direct links:
Well, yes, that's no problem. I was just demonstrating a bug for you. I will leave it in place, although I have fixed one of the two images as described in Thread:935527. The other image remains unrecognized.