This is by design, A lot of games won't show the total memory, they show the total free after the reserved portion the engine itself uses before counting in the graphics options changes. Gears 5 is another game that displays max free memory as less than the total.Just kidding, or maybe it changed on me but just booted it up again and it is showing 9303 MB for me. Well just add to the list of funky things going on with the game. Glad to know its not just me.
Also the benchmark in DX12 always freezes on the 4th scene (first one of the town) where it is night time and the lantern turns while screen is panning. It freezes when the camera starts panning and I have to force quite.
No issue with Vulcan. Using an Intel CPU.
My 2080ti also shows as around 9.4GB