Odd reaction to an OBS call

[Dakota]

Last evening, 14U ASA fast pitch game. Single umpire (me).

Batter hits a fly ball into right field which falls uncaught. F9 is chasing it down as BR attempts to round 1B and gets tangled up wtih F3 who is standing on the base.

I signal DDB and verbalize OBSTRUCTION.

BR turns to return to 1B. 1B coach tells her "he's giving you 2nd." BR touches 1B, my arm drops. Coach again says, "He gave you 2B." Ball is into the infield by now (F4 has it). BR trots on to 2B while F4 casually tosses the ball to F1.