I'm having similar issues understanding the relationship between full well capacity and gain as shown in this question here: Reconciling gain (e/ADU), full well capacity and ADC bit depth
The difference here is that rather than having 'extra electrons' being accumulated after saturation, I seem to have more gray levels available.
My camera is a FLIR Blackfly 200S6M, the EMVA 1288 performance is found here: http://softwareservices.flir.com/BFS-U3-200S6/latest/EMVA/EMVA.html
According to the specs, the system gain is 0.24 (e^-/ADU). Given the 12-bit ADC, I calculate that it takes 17,062.5 electrons to reach full well.
The listed saturation capacity in electrons, however, is listed at 14,837, quite a bit fewer than ADC saturation.
Am I overlooking something?