I have for a long time used Sports Tracker for cycling with an offline Google map of the area with no issues.
In the current version it no longer works sadly. It shows a message line ‘map offline’ on the display and if I go off the map currently cached to screen there is nothing.
I updated maps and re loaded the map of the area. I even thought maybe the very old phone I used as a bike computer was now too old so I moved onto a spare Samsung S7 but its still the same.
I particularly use sports tracker for this ability as I can have mobile data off and use a cheap SIM for emergency calls only.
The app seems to only be fetching maps data direct from the net now and ignoring offline maps.