Block State "occupied_bit" is not working as expected

The block state "occupied_bit", should verify if a bed is occupied by a player or a villager, but the block state is not working as expected:

Steps to Reproduce
1. Place a bed
2. In a command block (always active), write "testforblock (bed's coordinates) bed ["occupied_bit"=true]"
3. Spawn a Villager nearby
4. Set the time to night
5. When the villager sleeps, place a comparator in front of the command block

Expexted Results
The text "block detected" appears and/or the comparator activates itself

Obtained Results
Nothing happens

Note: It only works when you also specify the "head_piece_bit"=true/false". "direction" also doesn't work without it. Moreover, only when the bed is occupied by a player, it can be detected, it doesn't work with villagers.