Flaky for me too and it has been for the last 4-5 weeks:
ROMs tried: 7.1.1 and 7.12 ROMs like Resurrection Remix, PureNexus, PixelDust (my current one with 7.1.2 May update).
Cables I've tried: Google official cable for the Google Pixel (I have the Pixel not the XL), iOrange braided USBC to USBA cable
Vehicle: Audi A4 2017
Symptoms: sometimes when I connect my phone to the car via USB, the Audi will say please check your device's screen for instructions...a few seconds later, car will just disconnect. I'll notice on the phone that Substratum will say that Google Play Services keeps stopping.
What helps:
- A fresh reboot. It's not definite yet, but because this ROM has the ability to change auto-start / keep awake / run in background for apps, for both Google Play Services and Android Auto, I just told it the following:
- Don't keep in background
- Don't keep awake
- Allow auto-start
- On fresh reboot, don't connect USB cable until car starts playing music over bluetooth.
I don't think it's an issue with my USB-C connector but i'll try cleaning it per the suggestions here. Haven't tried that yet.