No heat with auto fan

Thought this was working fine but lastest cold front came through and stat didn’t turn the heat on. (been using AC last couple weeks). Said it was heating but no heat no fan. SO turned the fan to manual (instead of auto) and it blew and the heat came with it. Any ideas? Like I said- had been working for a good month without issue- both heat/cool so unlikely wiring issue. Was there an update recently?

Could have been an update that changed something. Check Settings>advanced>fan delay. If you’ve got a heat pump, it should be set to a 10-15 second delay