twrp not able to stop OxygenOS8.0.0 (stockrom) on OnePlus3 to overwrite recovery.

[MysticJay]

• [x ] I am running an official build of TWRP, downloaded from https://twrp.me/Devices/
• [ x] I am running the latest version of TWRP
• [ x] I have read the FAQ (https://twrp.me/FAQ/)
• [ x] I have searched for my issue and it does not already exist

Device codename:
OnePlus3 (OOS8.0.0)
TWRP version:
twrp3.3.1-0-oneplus3

WHAT STEPS WILL REPRODUCE THE PROBLEM?

twrp not able to stop OOS8.0.0 (stockrom) to overwrite recovery
flash TWRP using fastboot
reboot from Devicemenu, selecting "Recovery"
OR
reboot using VOL-
wait for TWRP start screen
reboot from TWRP menu to system
wait for system to load
try to reboot into recovery
Stock recovery is back

WHAT IS THE EXPECTED RESULT?

"Once TWRP is booted, TWRP will patch the stock ROM to prevent the stock ROM from replacing TWRP"

WHAT HAPPENS INSTEAD?

device boots into stock recovery

ADDITIONAL INFORMATION

maybe coincidence and different problem:

after booting into TWRP
"ADB backup --twrp" does not work
"ADB devices -l" does not show the device.
after booting into OOS "ADB devices -l" works fine

/tmp/recovery.log:
dmesg:

[bigbiff]

Have you tried 3.3.1?

[MysticJay]

sure that was a copy/paste bug. changed in the report.
maybe we remove our comments to avoid confusion

[Osndok]

I'm effected too, so I might be able to help if you have any diagnostics you would like to try.

[MysticJay]

I've had Oneplus support on my phone, They reinstalled everything.
Phone is working fine now and APPs complaining als work now.
TWRP ist not installed, the Phone is NOT OEM unlocked any more.

I have no clue what was wrong.