When disconnecting from the server, any cats owned by a player have a chance to not sit down/lock chests. This has been extensively tested in spawn chunks:

If another player is present near the cat when the player logs out, the cat will sit normally, locking a chest and triggering a redstone signal. However, if this is done in the absence of another nearby player, it fails to trigger 50% of the time for seemingly no reason.

This issue is only affecting Spigot - testing this in vanilla and Paper server versions causes the cat to sit and lock the chest 100% of the time, regardless of  the presence of other players.

Modifying spigot yml settings did not affect this in any noticeable way. 

Attached is a screenshot of the redstone device used for testing. This is normally used for wireless redstone to trigger an ender pearl stasis chamber.

The only loaded plugins are Floodgate and Geyser, which cause no issues when loaded on a Paper server.