After recently installing A1 Click Ultra Cleaner I was reasonably happy with the results While it did not remove all"problems" it explained that this could be because either they were open files or folders that were not empty. I generally had less than 1 MB of unresolved issues.
However, after now doing several consecutive cleanings using the "Clean PC "option it detects 548 MB of space being affected involving some 48 problems. The last run only cleaned 2 of 48 problems. 548 MB is a lot of disk space to be ignored. I notice these 46 problems all involve Temp files. For example:
My guess is that the Time Buffer checkbox in Cleaner Settings was checked. The Time Buffer protects you by not deleting files that are less than 7 days old, but it does mean that not all junk files get deleted. In time they will be deleted. If you want all files to be deleted no matter how recent they are, simply uncheck the Time Buffer checkbox.