I bought a stack of ten, but they didn't show up. I thought I might have missed a confirm window, so I tried again, but they still haven't appeared. The scales were deducted though.

I currently see that you have 3 separate stacks of LGMs in your Inventory with 8, 9, and 9 stacks respectively. Are they it?

Unfortunately, the Scale Shop stuff isn't tracked I don't think. It's such an archaic system and virtually nothing has changed with it in literally years and we've never had any issues with it, so I've just kind of left it alone. I don't really have any way to verify or look up purchases from there.

I can't find any stacks, and LGM doesn't show up as an option when trying to mutate my tamed themed.

Here's a screenshot of my entire inventory, and one of the menu when trying to use them. If I'm just being blind and overlooking the obvious, I apologize, but could you please point out which page and slots they are contained in? I just can't find them.

I haven't used any, so I can't imagine why they'd be 9 stacks instead of 10. I had thought I had some leftover, but when I didn't find them anywhere that's why I bought new ones.

This is definitely becoming one of the weirdest glitches I've encountered.

I was not seeing them in your Inventory either.

I went ahead and manually placed them into your Inventory.