I got the same issue with the DJI go 3.1.2, luckily I didn't have to RTH and so the drone is still here, but I do have the current location (the big red dot) about 1 km off. And the distance shown in the bottom right corner is non sense (btw what's the difference between the distance D and the one shown with the icon??).
Also got issues with weak signal/disconnected after 100m, video lag and jttering and the descending speed was somewhat lower (not sure if that is normal), max 2.5 m/s.
After a simple test it seems that the home point bug is related with the map settings for China mainland (General Settings -> map section). In particular by default I had "Enable AMAP" disabled and "Calibrate Map Coordinates" enabled (I live in Europe). When I enable AMAP and restart the app then the map shows the correct location (but Chinese characters over the map), didn't have the chance to check if the distance was off with this on.
So definitely a fail from dji devs/qa, will revert to a previous version