Will return to the field and do some error probing but ideas are welcome...
Can you check if lat and lon are correct in /etc/rbfeeder.ini?
sudo nano /etc/rbfeeder.ini
Fix them :)
(Press Ctrl-O and enter to save, then Ctrl-X to exit)
(That's about the only possibility i can imagine.)
I checked locally, putting in a position about 10 longitude to the west of your own position produces bogus positions.
After fixing the location you also need to stop rbfeeder or switch off the RPi for a couple of minutes, otherwise the feeder continues to be confused.
Using receiver local CPR is really a bad idea for feeding, just in case a developer is reading here :)
Stopping rbfeeder:
sudo systemctl stop rbfeeder
starting it again after a couple of minutes:
sudo systemctl restart rbfeeder