Just reporting back what fixed this issue for me…
I had to configure the “Config Bits” on my AD2PI from c08e to the default of ff04. I don’t know how the config bits changed from the default, but my limited understanding is that this is what controls the format of the messages from the AD2PI that HA reads for zone state changes.
After changing the “Config Bits” back to the default of ff04, I noticed the zone state change message for zone 2 changed from:
!CRC:!EXP:00,02,01,0be1
to:
!EXP:00,02,01
Note the missing !CRC prefix and what looks like a checksum at the end of the message.
See Protocol - Alarm Decoder Wiki for details on how to change the config bits.