Recently my waze notifications have stopped working correctly. Wondered if there is a trick to this or if it's a known issue?

Background info: iOS 10.3.1, Waze v4.22, BMW 2 series (2014).

The option to play sound as Bluetooth phone call was previously working very well. However now when plugged in via USB to charge whilst driving, if listening to the iPhone waze will interrupt the music through USB connection to announce turn instruction or hazards etc. However, if listening to the radio the hazards flash up on the phone screen but neither the hazards or turn info are pushed to the car via Bluetooth (previously this worked flawlessly).

I have experimented with all 3 settings in settings>sound>sound output to no avail. I have sometimes got it working for a few minutes when first getting in the car but then it ceases to work. Alternatively unplugged from the car the feature still works well. But I tend to always plug my phone in to keep the battery topped up so that wouldn't be an ideal solution moving forward.

I do also often now get a notification on my phone to say only one device can be used at one time: "cannot use accessory. Only one accessory at a time can be used". It's like the USB and Bluetooth connection via the waze app are competing for control. I checked that Bluetooth phone calls still work whilst connected via USB and they do for both outgoing and incoming calls.

Has anyone experienced anything similar or found a solution to this? I scanned the forum but didn't find anything recently relevant. Unfortunately I do not know if this is linked to the recent waze update or the iOS update. I have everything on automatic update so I don't really track what updates when.