FYI, in all the following instances and various games/racing sims, the shifting option in the assist menu is set to manual.
I’m playing Forza Motorsport 7 (FMS7) on Xbox Series X (XBSX). I am using a Logitech G920 Driving Force wheel and pedals(I don’t have the G920 Driving Force stick shifter). Up until 7/12/2021 I had been playing Forza Motorsport 7(FMS7) on Windows 10 PC where I had used G920 Left bumper/flappy paddle to shift down and right bumper/flappy paddle to shift up. I received my XBSX on 7/13/2021 and upon the first test drive playing FMS7 on XBSX using G920, found that the left bumper/flappy paddle did nothing and the right bumper/flappy paddle changed camera/view and I was forced to change gear with X and B buttons.
I went to the FMS7 controller options menu where the default preset button/control layout #1 was selected. Button layout 1 showed that the L/R bumpers were assigned to shift/change gear. I applied Layout 1 and started a new race. Despite selecting the button layout with L/R bumper assigned to shifting/gear change like I wanted, there was no change in the assignment of the G920 bumpers/paddles(i.e. left bumper/paddle still did nothing and right bumper/paddle still changed view) . I quit the race, went back to the options menu and changed to preset button layout 2, applied it, and started a new race. There was still no change in assignment of G920 L/R bumpers/paddles. I repeated this process, sequentially changing to 2-3 more of the FMS7 preset button layouts with no change in L/R bumper/paddle assignment.
To be certain this was not a physical hardware issue with the G920 wheel itself, I tested G920 with Forza Horizon 4 on XBSX and tested G920 with F1 2019 on XBSX. In both instances with both FH4 and F1 2019 the G920 was 100% functional with the left and right bumper/paddles shifting/changing gears how I wanted them to.