I’ve been trying to make a custom Accessory

but this keeps happening:
I’ve searched everywhere and many other people have the same issue but I have’t seen any solutions.
Edit: I found the solution, turns out “WrapLayer” was an actual object thing I had to put in the meshpart. But i’m having another issue, when I try to use the Accessory Fitting Tool and I select the meshpart, this happens:
I’m not sure as to why this is happening, if you know of a solution please let me know, thanks.
Edit 2: It worked, but I had to delete the WrapLayer first. Weird.