I tried the cap file you posted. I managed to get the collisions working for all sides by copying and pasting the original collision event you had and changing offset to (-10,10).
End Result:
2 same events, 1 with (10,10) offset, other with (-10,-10) offset.
Edit:
You can also duplicate the conditions within the same event line and just evenly divide them in half with the System's OR condition.