Proximity sensor malfunction resolved. Just before flashing the ROM I decided to protect the display with glass, unfortunately with glass that has a narrow but black frame. And that's the problem!
I need to find some frameless glass...
The 2 comments above say the proximity sensor issue and error dialog were not this rom's fault. Are there other issues with latest version?
NFC will be a problem in everything based on OSS.
Actually, i did try yesterday and I am in the same situation.
Recovery must be decrypted manually (No recovery can decrypt the phone on the fly as of now), so either flash a decrypt zip file or use the TWRP advanced options to decrypt the phone (note that you need to have the RW option turned on to decrypt the recovery and which will require formating the data partition, so backup.)
Either use the last (july) twrp file from https://androidfilehost.com/?w=files&flid=322792 (works fine), or if you want you can get the newer one from https://t.me/PocoX3OfficialUpdates (search for "brigudav" and download the august build)
*** Disclaimer I am not responsible for any damage you made to your device You have been warned