Current location is incorrect

[NekiMedo]

Replaced my old (6.5 years old) phone with a new one and migrated OsmAnd + (version 4.8.6) by exporting/importing Settings and My Places. Not sure if that's the recommended way to migrate the app but this operation seemed pretty successful (Tracks and My Favourites are there) except that current location on the main screen is not shown correctly - it's off by a few hundred meters and does not move when i walk around. The top right corner widget about satellites always shows 0/0.
GPSTest application works just fine and shows location correctly. Also, the Maps application (a fairly simple one) that came with the phone shows location correctly but I'd prefer to keep using OsmAnd.
Downloaded the "nighly" version of OsmAnd (v4.9.0#3364m) and it is a mixed bag - sometimes it shows the correct location and then jumps to either a new incorrect location or to the same incorrect location that OsmAnd+ shows. It seems the nightly build recovers the correction location if i go to some settings menu and exit back to the main screen - but after a while the location icon jumps elsewhere.
Any idea what is going on here and how to fix the location (preferably without wiping out all data)?