I have a Nexus 6 using a custom ROM - I've tried several over the years. Tomtom works absolutely fine on all of them, but... every time I install a new version I have to download the map again (Europe, over 7GB) even though the map is still in my internal storage. I'm guessing that some sort of link is broken between the app and the map, but surely there is a way to make the new ROM recognise the existing map instead of starting from scratch - a great deal of inconvenience for me and also for Tomtom in having to unnecessarily feed the map again. As commented in another thread, at least two major GPS competitors don't have this problem, since they can see their existing maps.
Does anyone know how to make Tomtom recognise the existing map?
(If a Tomtom employee reads this, please do not tell me "We don't support custom ROMs." This is a cop-out - exactly the same question would apply if I reset the phone to a stock Android version.)