Supported file formats. Desperated to find work around.

I am experiencing weird problem. My MPC gets stucked when I try to load my main drum breaks. Even when it is not getting freeze I get error 404 when I try to load some of them. It works fine everywhere except MPC 4k. It is essential for me to find workaround as I really need it for my work.
I've noticed when I try to load file bigger than 12 MB I get fatal error. So maybe it works similiar with bigger folders (500 MB of sounds) and it's getting freeze or maybe it's about supported file formats? Ak.sys couldn't handle it also. Anyway what are file formats supported by MPC 4K? 'Cus I'm considering converting all of them to .wav ...
I know I should read manuals, but I can't handle all this crap at the same time and I really need it fast.

It's easier to read the manual than having someone waste their time writing a bunch of stuff that's already out there. I'm really confused as to what type of problem you're having. I guess if you're going to import and work with file formats, it's best that you put them in data format rather than the customary standard format that's mostly used.

That's the best I can offer from the info that's given.

Seems like I've resolved the issue. MPC couldn't handle it from pendrive and there was files that was too long. I'm still getting seek error(404) when I'm trying to load some of them. When I was working on Reason I remember it couldn't audition some of them. This files was all in .wav format from the start so I didn't had to change anything.
Anyway I have no idea what data format is. Could you?