I did a clean flash.
Flashed the new 18.1 recovery to bootloader, rebooted to recovery, did a factory reset/data wipe, then flashed 18.1, Magisk and MindTheGapps, reboot.
All smooth as silk (takes me only a few hours to rebuild).
Verizon works right out of the box, as does Android Auto.
I tend to do clean flashes when moving between major versions. You can get away with a dirty flash sometimes, but I believe it's risky. That's why Lineage doesn't let you move via OTA.
Oh, and yes, each nightly updates the recovery, I believe.