Can you please tell us exactly which ASI120 you have? Do you have the "old" ASI120MM or ASI120MC (USB2 version) or the "new" ASI120MM-S or ASI120MC-S (USB3 version)? The reason I am asking is that the old USB2 version no longer is supported on Linux, which may be the cause of your problems.
Thanks for the information. I have an ASI120MM-S (USB3) and an ASI1600MM Pro (USB3) as well. For the ASI120MM-S I didn't have to do anything but go to the Guide tab, select a 2 seconds exposure and click the loop button. For the ASI1600MM I had to set the gain to so called unity gain (gain=139, offset 21) in order to see anything but noise. This needs to be done in the INDI Control Panel.