If you remove shore power or gen power and disconnect the battery, wait about 10 seconds the PD will reset mode and will be in Boost 14.4vdc when AC is restored and the battery hooked back up.
That's the only way what you described can happen unless there is something wrong with the PD..
When you disconnect shore power the PD control electronics is kept alive by the battery, thus still alive.
Jim
2000 2500 9.6 Bigfoot,94 F250, Vision 19.5, Bilstein shocks, air bags/pump, EU2000, PD 9260, Two Redodo 100ah Mini's, Aims 2500 Conv/Inv, 200W. solar, Morningstar Sunsaver 15A/ display panel, Delorme/laptop for travel, Wave-3 heat.