Regarding the SIM2 SMS bug which was closed in the bugtracker
https://bugtracker.fairphone.com/project/fairphone-lineageos-on-fairphone/issue/6
I know that this bug is fixed in LineageOS BUT as stated in differend post in the Lineage OTA thread
and also in the bugreport from @freibadschwimmer
https://bugtracker.fairphone.com/project/fairphone-lineageos-on-fairphone/issue/14
this bug still persist in our Lineage ROM till now.
After some peeking around in logfiles and with regards to the different SIM bugs in the bugtracker and here at the forum, it looks like that we have a problem with the communication between
OS ↔ RIL ↔ MODEM
As RIL and MODEM are binary objects from Fraiphone/HW Vendors and also used in the FPOS/FPOOS builds without the problems we have in Lineage, perhaps there is some ill communication between OS ↔ RIL.