Not talking about what you figured out - I am talking a huge difference in a setup when your HA vs when its a single box, etc..
Did you validate pfsense is seeing the dhcp discover? Troubleshooting dhcp is 30 seconds worth of troubleshooting here... The dhcp service is running or its not running, it sees the discover or it doesn't does it send a offer...
@Gertjan list is pretty spot on to be honest ;) hehehe