I had similar problems when the dealer put the "service sticker" over the GPS antenae (near the RV mirror)
once removed & cleaned it was back to normal.
However the map data is CRAP & a recent quote for new data is $195 with no guarantee at all that the data
will be accurate or even up to date (last 2019 update was 2017 data!)
I'm still encouraged to turn right at a No Right turn that's been there for >20 years! (Apple/tomtom/google know about it!)
Despite updating the map data myself at https://mapcreator.here.com
on the advice of the dealer!
What a crock the nav system is!
Is there a way of getting an apple/google play app for the thing perhaps?