TPS6594-Q1: Flashing stops with error message

Team,

my customer wants to use LP8764-Q1 and TPS6594-Q1 in a new project. NVM configuration of LP8764-Q1 works like a charm.
NVM configuration of TPS6594-Q1 however, fails with error message „failed to unlock eeprom“. Register-/adress-validation works, but not the actual flashing process.

Is the flashing process for TPS6594-Q1 different from flashing the LP8764-Q1?

Thanks