many thx for pointing to this!
There is a commit from Dees_Troy which seems to be related Fix restore of subpartitions
I cannot say for sure but it sounds like this is the reason for the problems.
Currently waiting for feedback of the devs to confirm...
ok fully confirmed:
Due to a bug
in the twrp sources regarding the subpartition handling some partitions which gets grouped like EFS (modemst1 + modemst2) were not able to be restored by twrp. It seems this bug was introduced somewhen between the android-5.0 repo (official twrp) and the android-6.0 repo (my twrp).
The only partitions in our device which are based on subpartitions and used in backup are EFS related. /data, /system, /recovery or /boot should all not be affected by this bug. So restoring your device should work with build#091 or newer (as reported by 2 users) as long as you do NOT try try to restore EFS. This is untested by me but as long as this is the only bug it should work without problems.
Just to clarify things: I'm not a twrp developer. I use their code to build a twrp version for our device. TWRP is build by humans. Humans are known to make faults. So I really appreciate the work of the TWRP developers but keep in mind that every software u r using contains bugs. You may not know them (yet) but they are there.
fault was to not test EFS restoring before releasing. The main reason for this is that I have to do all tests on my daily driver which I really resist on.
To be able to get full support without any restrictions I bought a second device
yesterday for testing and developing only
! Yes you had read right! just for testing.. and no i have not too much money but i hate to develop on my daily driver + the current situation makes me mad. I hope to get the 2nd one in the next days..
After that I will build with the mentioned fix of Dees_Troy and will testing the backup and restore with both STOCK and CM based ROM on it - including EFS of course.
This will take some time so don't expect any updates until my tests reached the final stairs.
If you are brave enough: I always need testers. Send me a PM if you want to help. Create a backup with the official twrp first and then you are save to test the updated ones..
keep in mind that official TWRP versions can not always be fully tested by the TWRP devs!
They do not own each device they support so the same happened here could had happened in the next official twrp version
The only reason why it happens now
is that I used newer sources then the official released.