Works fine for me. I always fastboot twrp. Never flashed it permanently.Tested today again. Using fastboot to boot the twrp image still doesn't work for me, still stuck on the android one logo.
But I noticed that flashing the boot with it then going to the recovery work.
So I switched to the unused slot in fastboot(you can check the current one with "fastboot getvar current-slot" and change it with "fastboot --set-active=a" or "fastboot --set-active=b" depending on the one you're using currently),
then I flashed the boot with the provided twrp image. Once that was done I simply went to my phone's recovery where was twrp, switched the slot back to the original one using twrp and did my things.
Obviously do this at your own risk.
Booting twrp from fastboot for some reason never worked for me on android 10. Even after flashing a stock rom.Works fine for me. I always fastboot twrp. Never flashed it permanently.
This is working fine on my Nokia 7.1, but before every backup, I have to delete folder /data/per_boot otherwise backup fails.
TWRP 3.4.0-0 , for the Nokia 7.1
Source Code: https://github.com/TeamWin/android_device_nokia_CTL_sprout
My build script https://github.com/RaghuVarma331/scripts
Current Stable Version: 3.x
Stable Release Date 2019-01-26
Last Updated 2020-06-25