I don't know about the R1200R, but the R1200GS uses a fuel sensing strip instead of a float to measure how much fuel is in the tank. Many GS owners experienced failures of these strips. I wouldn't be surprised if the R uses the same system, so you may have that same problem.
I owned 3 GS bikes before buying an R, and got into the habit of resetting the trip meter at each fill-up, just in case the fuel strip failed (it never did). Since I know about how far the bike can go on a tankful, the trip meter can be used as a backup if the fuel gauge fails.