During any activity that uses a map (hike, walk, run, cycle) the map has a blank background - how do I change it?

Hi all, hoping someone can help me.

During any activity which uses a map, such as hiking, walking, running etc - the map only shows a blank white background. The GPS is enabled, and my phone has signal. Toady, I downloaded a map from All Trails and saved it as a course, which I hoped would work, but when I tried to use this on the hike today it showed the same blank white screen. The route red line was there but there was no background on the map, so it was really difficult to follow.

Hopefully I'm missing something minor and this is a quick fix. My husband has the Fenix 6 Pro and his loads maps without an issue - it shows contours of the terrain and roads including road names. Much easier to look at!

I've already tried a soft reset, and a full factory reset, but nothing has worked. The GPS definitely works, because the activity shows with an accurate map on the Garmin / Strava app once it's finished and uploaded.

Any help is greatly appreciated!

Thanks.