@Nick-Carthew As promised I did another test today in the car. I used my phone in the car, not connected to the car so with Audio and navigation directly from the phone.
MRA navigation:
I started the navigation with phone screen active and everything worked obviously fine. I used the on / off button to make the phone screen inactive and immediately when the phone was inactive the voice guidance stopped. Apparently not only the voice guidance stops when the phone is getting inactive but the whole navigation is interrupted because when switching the phone on again it jumps to the new position. So I think its clear that for some reason the app is now working when the phone is going inactive.
google maps:
I did then exactly the same test with google maps. I started the navigation and everything works. When I switched the phone to inactive with the on / off button the voice guidance continued as it should and apparently also the navigation continues in the background because when you make the phone active again its in the correct position, not jumping to that.
I also did another thing, when you touch the screen on the phone to make the screen active but your face in not visible for face time, meaning the phone will not be unlocked, then you can see a message on the home screen as in the below picture indicating that a navigation is active. In addition you could see in the upper left corner of the phone screen the blue mark that something like a navigation is running in the background which is not the case on MRA navigation when the phone is locked.
So I am still certain that this is a problem with the app and not with phone settings, memory or RAM etc
