Sorry I left a a few of you guys hanging without response, I had almost forgotten I ever owned an Acekard they took so long to ship me the new one.
Anyway! It turned out it WAS the Acekard itself, it was faulty somehow, using the same microSD and everything it works just fine. It was a legit card, just didn't want to run save files for some reason.
I just wanted to say thanks to everyone who tried to help, I really appreciate it. I was petrified it was something wrong with my XL and a new one wouldn't help me at all, but it works great. This one even fits better and doesn't require the paper trick to keep itself in place.
If someone has a similar problem and you've ruled everything out, just return it and get a new one.
Anyway, thank you all again; and happy holidays! 8D