The bed set by the /fill or /setblock command is not full

If you put the bed in the usual way, it will be full, but if you do the same with the /fill or /setblock command, it will not be full. How to reproduce:

Replace the block with a bed using the /fill or /setblock command.

Expected result: the bed set by the /fill or /setblock command will be full.

Actual result: the bed set by the /fill or /setblock command is not full.