What was your installation procedure? Sounds like a problem that occurs sometimes when a flash is done over a previous installation. Try a full wipe and clean install. Setup always allows me to restore apps and recent calls/texts but for more security you can download an SMS backup app if that's important to you.
The gapps arm Pico version is what I download and use.
Do you know how to view your apn settings?
I'd do a clean install and see if you still experience problems.
Besides Bluetooth calls not working still this ROM has been working fine as my daily driver.
I upgraded from DomPop TekHD ROM. I did the wipe (system, dalvik, data, cache), then installed the ROM.
I noticed the modem is still at N900TUVUFOB6. I'm trying to update to N900TUVUFQD2 (I read online that's the baseband to use for LineageOS 15.1) multiple times but it either gave me unknown baseband or back to FOB6. Does your ROM use FQD2 modem version?
Should I do complete install with official FQD2 ROM first before installing your ROM?
Or wiping the internal storage will help?
I know where the APN settings is. I compared it with Tmo APN online and they look the same.
Thanks.