Absolutely same problem here -
Tested on 2 ASUS Laptop with:
Windows 10 Pro 64 bit v. 1803 including all current updates
CCleaner v5.44.6575 64 bit free version.
When my laptop starting up - in tray icon I see for a few seconds the icon of CCleaner and after that its gone.
When I check manualy after that - I see many files for cleanup -
So I confirm - CCleaner v5.44.6575 not delete them at startup.