Opened inventory via E, then tried to close inventory again with E, but it didn't close the inventory and just re-centered the cursor in the middle of the screen.
Happened in both Survival and Creative.
EDIT: When trying to get to the automatic search via pressing T in the creative inventory menu, inventory was exited and went straight to chat. Inventory was in search mode when re-entered via E.
SECOND EDIT: Pressing E inside the creative inventory search screen will just erase the current search and do nothing.
Confirmed, also with other Keys (I'm using "X" and got the same issue)
Might be caused by the fix for MC-29469