giancarlo Hi, giancarlo!
① In ASIStudio, "Low" gain equals to "highest dynamic range" gain in ASCOM, "Middle" equals to "unity gain", and "High" equals to "lowest read noise". If the "highest dynamic range" is equal to the "unity gain", there is no "Unity Gain" in ASCOM, so there is no "Middle" in ASIStudio.
② Please confirm that the star is big, distinct enough and the quantity is enough. You can adjust the Exp, Gain, focusing to try the live stacking function. If the problem still exists, you can save several fits images and
send them to us. Our email: firstname.lastname@example.org
Thanks a lot.