Strange central lock behavior

[Cornerlot]

Before I spend hours trying to sort another electrical gremlin I thought I'd ask first.
On a 1981 with power locks ... Start with the doors unlocked. When the ignition key is turned ON (engine running or not) then the key is cycled OFF, and next you can try to pull the inside driver's door release. But, the doors will then lock themselves before you can open the door. The normal turn of the door power lock knob unlocks them to let you out.

Any thoughts where to look?

The power locks work normally if the knob is cycled lock/unlock/etc.