running CCleaner every now & then skips these Photo app files. Only way to fix is reboot laptop & rerun Ccleaner. Windows 10 pro current version & updates
When something gets skipped it's (almost always) because that application is still open or still running in the background.
(If CCleaner isn't asking you if you want to close it then you've clicked on 'don't show this again' at some time in the past).
Rebooting the computer closes the running app, and so then CCleaner can clean it.
Windows Photos/Microsoft Photos will launch itself in the background at times to do searches or 'photo enhancement', which can cause problems, although it should stop when you start using the computer again it doesnt always stop straight away.
This is a bit old but it might help: https://www.tenforums.com/performance-maintenance/7781-photos-background-task-host-high-cpu-usage.html