Resolved! STM32L4R: How do Flash Option DBANK and DB1M interacts?
In FLASH_OPTR, both DBANK and DB1M are r/w and have no restrictions beside that PCROPA/B needs to be disabled. For 1M device there are two(?) sensible settings DBANK=1, DB1M = 1 for 1Myte dual bank continous modeDBANK=0, DB1M = 0 for 1Myte single ban...