I have a similar issue. Windows 10 [Version 10.0.18362.295], Immunet [126.96.36.19955]. Installed Immunet just yesterday.
When I tried to start a scan (full/ flash/ custom, all the same) Immunet did nothing. CPU usage = 0, HDD activity = 0. I scheduled a flash scan for then next minute, and it didn't do anything either. No error messages at all, it just does nothing. I have restarted the computer and reinstalled Immunet, no effect.
Then, for no specific reason, I tried running the client "as administrator", and voila! The scheduled flash scan (or the initial setup scan, cannot be sure. History only says "flash scan") started and finished. But again, when I try a manual scan, it does nothing, just like before.