why is Zoom skipped until third attempt

[S T]

I have to run Cleaner three times to get it to clean Zoom, no matter how much or how little there is to clean in other programs.

Why doesn't Zoom get cleaned the first time through?

[nukecad]

Is it saying that Zoom has been Skipped?

When an item is 'Skipped' in Custom Clean it's generally because it has files open, CCleaner needs apps/files to be closed so that it can clean them.

Sometimes when you think an app has been closed it will still be running in the background.
And sometimes that can be simply because it's taking a while to fully close, and you are trying to clean before it has finished closing.

So it may simply be that your Zoom is taking a while to fully close for some reason (maybe there is even still an open connection until disconnected at the other end?), then once it has closed CCleaner can clean it

By default when an app is open and so preventing cleaning Custom Clean will show you this message asking if you want to close the open app:

but if at any time you have ticked "Do not show me this message again" when you get that message for an open app then in future, if it's open again, CCleaner will just Skip the cleaning of that particular open app without asking.

eg. Here I had both Firefox and Zoom open when I ran a clean, and as you can see both have been Skipped:

Once I closed Zoom then CCleaner could clean it (but Firefox was still open so was still skipped):

[S T]

Yes, it says Zoom 'skipped' twice.  I don't do anything except run cleaner a third time, since Zoom is already closed.

it is consistent, always cleaned only on the third attempt. That is true whether or not the browser is correctly skipped because it's open.

Zoom is always skipped twice before being cleaned the third time.

[nukecad]

Mmm, next time before you clean do an Analyze and if it skips Zoom then before cleaning look in Task Manager and see if there is anything Zoom related still running.

Although I do have Zoom on this machine I've only ever used it once, to attend a funeral service remotely, so I'm not very clued up on what kinds of processes it runs.

One thought though, are you logging in with a Zoom account or are you using your Google or Facebook account to log in to it?