Steps to Reproduce:

Spawn shulker at a Y level that is a multiple of 16 on the underside of a block
Place pressure plate one block below the shulker
Get the shulker to open (switch to survival)

Observed Results:
Pressure plate will fail to activate when the shulker opens.

Expected Results:
Pressure plate should activate when the shulker opens.

Notes:
I have tested at every Y level in 1.19 and for completeness the Y levels at which a shulker do no activate a pressure plate below them are; 304, 288, 272, 256, 240, 224, 208, 192, 176, 160, 144, 128, 112, 96, 80, 64, 48, 32, 16, 0, -16, -32, -48.

I have run some smaller scale tests that show 1.18.2 does not exhibit this behavior while 1.19.1_rc3 does.

Code Analysis:
Code analysis by Volbla can be found in this comment.