Perhaps an issue with Unicode text?
https://community.openstreetmap.org/t/cant-authenticate-maps-contact-seller-for-help/87406/2
I stopped making Garmin maps some time ago myself, and no longer even use Garmin devices, although I used them heavily at one time. It's pretty clear that Garmin doesn't want people to use third party (free) maps, they are desperately hanging on to a dying business model. But it would be surprising if they actively started blocking all third party maps.
I have read that (some) newer Garmin devices are blocking routable openstreetmap maps, presumably over liability concerns that the routing may be defective and cause problems. No idea if that is true, but if so then it might only affect routable maps.
https://community.openstreetmap.org/t/cant-authenticate-maps-contact-seller-for-help/87406/2
I stopped making Garmin maps some time ago myself, and no longer even use Garmin devices, although I used them heavily at one time. It's pretty clear that Garmin doesn't want people to use third party (free) maps, they are desperately hanging on to a dying business model. But it would be surprising if they actively started blocking all third party maps.
I have read that (some) newer Garmin devices are blocking routable openstreetmap maps, presumably over liability concerns that the routing may be defective and cause problems. No idea if that is true, but if so then it might only affect routable maps.