Umpires often call what they EXPECT to happen, or what they THINK they see. In this case, if she calls obstruction for "falling in" and you truly haven't moved a foot into the 0.9m distance, it's a hysterical and wrong call. You actually have to land either (A) with your arm still up or (B) too close for the shooter to actually move.
It sounds similar to the annoying event of the whistle going while the defender is still in the air for landing too close - jumping from a correct distance but the umpire calling obstruction before it occurs. Unfortunately players have to be aware that obstruction is an over-called rule by umpires, stepping and 3 seconds are very inconsistent, and a few rules like delaying play and replay are under-called.