Can't mount system as r/w on rooted device
Hi. I will try to give as much info as possible so bare with me.
I have a Sony Z1 C6903 on build 14.3.A.0.757 Android 4.4.2
I rooted it using a prerooted firmware method with duel recovery (I think by doomlord not 100%) which involved downgrading my firmware back to Jellybean then rooting it and then flashing the prerooted firmware ect..
The root method worked perfectly and my device is fully working, but just recently I tried installing the features for the camera from the Z2 which involves moving the apk to the system/app folder but none of the apps can mount my system as r/w, I have tried ES File Explorer, Root Explorer, Total Commander and even TWRP's built in file manager and all of which are granted root access by SuperSU but won't mount the system as r/w.
I checked with root checker and it says I'm rooted and all other root apps seem to be working fine. I also have an LG G-Pad 8.3 on kitkat rooted and a Samsung Galaxy S2 on Cyanogenmod 11 both of which can mount the file system as r/w and I've rooted a lot of other devices with no issue.
One thing that doesn't make a lot of sense is that none of the apps can mount system as r/w on my Z1 yet if I tell SuperSU to install itself to the system from its own menu it works with no problem.
I just need a solution to this issue and would rather not reroot it again as the root method for this device is a pita, it's also worth mentioning that I can't unlock the bootloader on my device to root it that way as my phone has "Unlock Bootloader Allowed:" set to No.
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