Can't modify and/or transfer files from the internal storage

A

AC Question

Hello!

After perfoming a factory reset on my phone, I noticed that some files and folders in the internal storage weren't deleted.

However, after deleting them manually they appear again for an unknown reason. Plus, I can't transfer files to folders that already came with the system (for example, the Music folder).

It seems like the internal storage became ready-only, but idk why this happened. At first I thought it was because of Xposed, since I had a bunch of modules, but maybe this has nothing to do with that...

This problem is also preventing browsers from downloading things, since they probably storage the files in the Download folder. The only one that wasn't affected was Maxthon (it has its own download folder).
Basically, the internal storage is apparently read-only and I can't modify or transfer files to it (it is "possible" to delete files, but they appear afterwards :p).

Can someone help me? I'm using a Moto G XT1040, Lollipop 5.1 and rooted.
Thanks.