I did the following for testing …
- Installed Fairphone OS 19.08.1, confirmed it boots and did initial setup.
- Installed TWRP 3.3.1-0.
- Wiped the phone strictly according to the guide step 4.
- Installed lineage-16.0-20191011-nightly-FP2-signed.zip, confirmed it boots and did initial setup.
So I can’t reproduce what’s going on on your phones, sorry.