I recently posted this issue too - and had another user recreate it. You’ll find that you can move forward after 3 clicks on FWD but then it will jump again and then the next time you will need 4 clicks, then 5, then 6 etc. Its an odd one but should be an easy fix for Denon.
Incidentally, I wanted to use the FWD/BCK for exactly the same reason as you - locking beat grids on a number of tracks quickly!