When a player rides a horse, donkey, or mule around sculk sensors or shriekers, they don't get activated. But if a player rides a pig, strider, or skeleton horse, it gets activated.
Steps to Reproduce:
Tame a horse and put a saddle on it
Place sculk sensors
Ride the horse around
Observed Results:
The sculk sensors don't get activated.
Expected Results:
The sculk sensors should get activated.
This also happens for other mobs. When a sensor detects a mob, it does not send any signals to the shriekers. Neither do other types of vibrations do, which does not make sense.
The shriekers function as expected in Java. Please consider this to be a parity issue.