I have a Nuvi 760 with a nüMaps Lifetime Europe subscription. The most recent map I have installed is City Navigator Europe NT 2015.20. When I connect my device to Garmin Express it is recognised and the serial number and software version are collected. However, under "updates" the "Your maps are up to date. Full coverage of Europe 2015.20" message is displayed, and the "Your device software is up to date" message is displayed under that. Only possibility offered is to reinstall the Europe 2015.20 maps, nothing more recent.
Grateful for any suggestions the community might have!