Today I tried to take flat frames with ASI533MC Pro, but I got this error. I'm sure that the format of the controls tab is 24bit RGB, but all captured images are 8 bit. The same settings works fine with my ASI182MM pro.
There is no proper ADU value for 8 bit since you should not take 8 bit images
For 16 bit many people suggest to have the peak in the middle (which would be around 32000 ADU) but I advice to go much higher (around 55000 or more as long as you don't get saturated pixels) to make the best use of the full dynamic range of the sensor.
The problem when using 16 bits images for flats is that after it starts capturing flats it saves them as grayscale images and I cannot use them to calibrate EGB images... Any idea how to save flats after calibration as RGB images?