FalconFour
Member
Moto G5 Plus here (just repeating for newcomersNexus 5x here. Works 99% of the time after turning off battery optimization for four apps/services: Tesla, Bluetooth, Google Connectivity Services, and Companion Device Manager.
Let me know if that improves the phone key.
My next clue is Android Wear (ugh... Wear OS, I hate that name). I have a LG Watch Urbane 2 that lives on my wrist so much I have a nasty tan-line from it and forgot all this time that it might affect things. It's always Bluetooth-connected. I'm starting to wonder if that's causing the problems...
After a little testing if the battery tweak on Bluetooth Share does anything, I'll try switching my watch to airplane mode (making it invisible to the phone) and see if that does anything next.