I have a personal mod pack that I made including Adventure Backpacks and Pixelmon, and w/ the new .8 update on Adventure Backpacks, I can't access the gui for it with pixelmon's gui overlapping it. Note, I do have Baubles as well, but I can't put on a backpack w/ it either.

This isn't horrible, but a later update with pixelmon compatibility would be nice. If needed I can show all mods I have in modpack to diagnose this.

(Edit) Sorry for my inaccuracy, I didn't realize how to put on backpack was by right-clicking at empty space and also didn't realize that in the backpack inventory hot-key access that I take it off. I'm sorry for posting a non-nonsensical post.