The controller doesn't immediately respond to Asiana's initial checkin, that's not unusual when it's busy.
There are two tower feeds. One has both ground and tower, so if ground is talking you won't hear tower. The other feed is just tower but this one seems to drop samples occasionally.
On the mixed ground and tower feed there is a second checkin from Asiana on short final, but this is not heard on the other feed. The other feed does capture Asiana's full landing clearance and readback, a small part of which can be heard in the background on the mixed feed. By listening to both feeds in parallel it's possible to determine that the clearance is given immediately after the short final checkin. "What happened over there?" is heard about 45 seconds after Asiana reads back his clearance to land.