Album art is displayed incorrectly

A

AC Question

I've recently transferred from Note 3 to Mate 9, and when I moved over all of my music they all lost their album art. Me, being the dedicated and patient person I am, went through all 650+ and re-tagged their correct album covers, as well as embedded them into the files.

However, once I opened my music player again (I'm using BlackPlayer Ex free apk, so the tagging was through that app) my album art were displayed incorrectly for some. Like, 100 songs had one album cover, even though they were from different albums. I checked through another app, this one specifically for tag editing), and while the thumbnails for the songs all had one image, the embedded image files were different.

Not only that, but some names had glitched to random symbols, and when I tried to edit them back to their original, they were tagged correctly already.

I downloaded 10 or so other music players to double check, and most of them were like this as well, with the wrong album art and weird symbol names. A few were the exception- Poweramp, stock Huawei music player, and doubleTwist. I'll be honest though, they all have terrible interfaces and I absolutely despise their aesthetics.

I went back through all songs again today (through Black Player again) and attempted to edit them correctly, once again it didn't work. Everytime I exit the app and come back on, a different image is displayed for the songs. This image changes between the images from my other albums.

I seriously cannot be bothered to go through all 650+ songs again and again hoping for something different each time. What is the problem? I'm a huge music junkie, and I haven't been able to organise playlists or stuff yet because of this album problem so I've been dying recently...please help!!
I really don't want to settle for any of the apps listed above, but if there really is no other choice I guess I will have to.