hi, had it been unused for a while with low fuel level.
If so I have found that fill it to the brim and it sorts itself out, something to do with it "drying out" if stands .
Explanation may be wooly but it has worked for me on a number of occasions.
Make sure the connector is both fitted correctly to the fuel sender and there's no water in it. I had this after I had cleaned the bike with the tank off and the canbus was shutting the sender down because of a short. Fuel guage showed zero with the yellow light flashing. Its the one next to the FPC, furthest to the left on the LH side of the tank. Its easier to get too if you take the LH panel off.