[Fixed in 1.14.30] Upside down shulkers are not attached properly to the block above them

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