Which maps are in Map list?
basemap is garmin north america
Look into nuvi and tell if you have a basemap covering the whole world, if it covers only America this is the reason of your problem.
No basemap for EU= no EU roads on nuvi.

something like this:
103747d1398094587 nuvi 3790 doesn t show map solved 15956

download [Only registered and activated users can see links. ] copy it to .System folder. and remove America only basemap.
Reset and restart nuvi.