When a shulker is going from the closed to open position, in between you are able to walk through the shulker and even stand inside of it. Tested in creative.
MCPE-18264
You are able to walk through shulkers when they are opening their shells.
Resolved
Fixed
0
(Unassigned)
Unconfirmed
Phone - Android - Samsung Galaxy Note
6.0.1
0.17.0.1
1.0.0.1
Retrieved
I have the same problem.