Hi,
go to Navigraph settings on the EFB, press few times “START THE AUTHENTICATION PROCESS”, authentificate yourself on navigraph page then exit the flight and go to main menu. The charts should work when you start next flight.
This problem is related to wrong ACCESS/REFRESH token and the steps above should fix the problem.
if the steps does not fix the problem then the problem should be fixed in few days because an update with brand new EFB for the A320 (with new SimBrief and Navigraph integration) is already sent to the approval process and going to be released in few days.
Kind regards
BetaCam