If you summon a sleeping cat or ocelot, it will only visually appear lying in the bed for 1 tick. Subsequently, it visually stands up and resumes its normal hitbox, even though it remains technically sleeping. This can be confirmed by damaging it, causing the cat or ocelot to be teleported to its wake-up position.

Reproduction steps

1. /tick rate 1

1. /time set midnight

1. Position a bed with its foot at coordinates 0 -60 18

2. /summon minecraft:cat ~ ~ ~ {SleepingX:-1,SleepingY:-60,SleepingZ:18}

   (You have the flexibility to modify the command coordinates if you've positioned the bed elsewhere.)

1. /summon minecraft:ocelot ~ ~ ~ {SleepingX:-1,SleepingY:-60,SleepingZ:18}

   (You have the flexibility to modify the command coordinates if you've positioned the bed elsewhere.)

1. Press F3+B
2. Damage the cat/ocelot

Observed: The cat and ocelot only remained lying in the bed for 1 tick. After standing up, damaging them resulted in teleportation to the waking up position, indicating they were still sleeping.
Expected: The cat and ocelot would remain lying in the bed even after 1 tick.