Normally titanium backup saves backups with its ownership, for example u0_a252:
-rw------- 1 u0_a252 u0_a252
539 2021-11-07 09:52 com.application.zomato-20211107-095236.properties
However, it sometimes saves backups with media_rw ownership:
-rw------- 1 media_rw media_rw 963K 2021-11-07 09:00 net.bikerouteplanner-667db7c2a87ed259454c457130013a1a.apk.bz2
The backup directory is in /sdcard/, internal storage.
These files can't be read by users, or even by root! It prevents me from easily syncing the files to an external server, or to copy them off before doing a factory reset.
I've tried chown in adb with su, but the the ownership isn't changed. The solution I've found is to reboot to the bootloader, boot TWRP and change it in an adb shell.
I've found nothing in web searches other than to use TWRP.
I found nothing going to the cause of the bad ownership other than perhaps android taking them as media files.
I believe the problem started with android 11.
I am currently running android 11 on a pixel 5, rooted with magisk.