What's Happening:
As shown in the screenshots, upside down shulkers are not properly attached to the block above them. When they open, when a player is within attack range, the gap increases quite a bit and look very odd.
What I expected:
I expected the shulkers to stay in their block space. I expected them to not float downwards when a player gets near.
How to reproduce:
Make a little platform and place a ceiling above it
Summon a shulker under the ceiling
Get a few block away and switch to survival
As the shulkers notice you, they should open and leave a 1 block gap between them and the ceiling.
Screenshots Attached: Yes
Appears to be fixed in 1.14.30 Hotfix.