Twrp resets itself, can't mount data or cache

[Hpm]

Hey guys, really sorry for not writing in German, but I'm simply not able to. Please feel free to answer in German, as I can pretty much read it, with a dictionary.
I'm running lineage is 15.1 on my shift 6m,and have installed twrp recovery.
I can't mount the data partition from twrp, so I can't back up, or wipe cache. It can't see my external sd card either, so "internal storage" is the only option under "choose storage"
Also, it doesn't seem to be saving changes. So if I adjust time-zone etc. it will have reset next time I boot, and it asks me on every boot to choose whether I want to keep my system read only.

I have tried to format my data partition, and that worked when I rebooted to recovery immediately, but when I rebooted again after setting up the phone, it had reset itself again.

Hope someone has as an answer,
Cheers!

 

[LuBo]

did you try to install twrp a second time?
which version of TWRP did you use?

 

[Hpm]

Yep - I tried reinstalling. It's the version linked to in the first post: 3.2.3-0 I think.
I've got the stock recovery on now, and it can access the sd card. It can't unfortunately do backups or access data, or anything, so I'd like to get TWRP working!