I have a Z6 which I use with an SB-400 flash. The combination works well.
However, in low light situations with the SB-400 connected and switched on, the ISO value displayed in the viewfinder of the Z6 shows a fixed value of 400 and the under-exposure meter is displayed. If the flash is switched off, the ISO value resumes its correct value, i.e. exceeds 400, and the under-exposure meter is removed from the display. Apparently this does not affect the operation of the unit; the camera and flash do take pictures with ISO values above 400; the only problem is the displayed value of 400 prior to taking the shot.
I realize that the SB-400 is no longer produced but the Z6 reference manual states clearly that it is compatible with the SB-400.
Can someone please help me to understand what's going on?
Does this happen as well with a Z6 and an SB-300?