Same behaviour here and I'm quite sure my phyiscal throttle levers are in sync.
Steps to reproduce:
-With throttle levers in sync (I'm only using the hardware levers to control them during the flight), I put the throttles in flight idle (still using the hardware levers) during the approach.
-At touchdown if I retard the throttles, it doesn't move to the reverse area.
-If I move the HW throttles forward a bit and then backward, then they cross the flight idle detent and go into the reverse zone.
Hope it helps.