OSM Map not working

for the first time I am using a GPS like this I got yesterday.
The Garmin etrex 20.
Bought it on Amazon and it came with a basemap of only China (everything outside of the borders of China is blue/Ocean)

I live in Japan though and would like to have a map of that country.
So I got the Japan OSM, put the gmapsupp into the “Garmin” folder in the SD card and installed it in basecamp mapinstall.
when I now open the “map” menu in the etrex20 I still am in the middle of the “ocean”.

So I go into settings → map and tried to figure out what I can do.
Disabled all maps and wanted to enable the OSM map but when I press “enable” it says I have to change to “automotive mode”
to get it to work.
Easy, I change the setting to “automotive mode”, go back and press enable on the map…but it says the same thing again
even though the mode is activated (for whatever reason)

I checked on the “map” option again but am still in the ocean and only see china.

I also have other maps and none work

I dont think this is a map related question but how to handle your device.
Please ask it on https://forums.garmin.com/tags.php?tag=etrex