Correct, I was actually running 5.44 when the problem occurred. I have since updated again to v5.45. I did some more investigating using a laptop with the same configuration as the affected desktop (same OS, antivirus, settings), only with CCleaner 5.43. Everything worked as it should until I updated CCleaner to 5.45, and I experienced the same issue of CCleaner indicating it was cleaning in the notification area, but no cleaning was taking place. I uninstalled v5.45 and reinstalled 5.43 (from filehippo), and everything works again. Based on this, I would say the problem lies with v5.44 and later of CCleaner.