Had “invalid pointer operation” with zip and download after trying in one of my projects.
Tried in general demo and same issue:
Seems to happen at random. First time files zipped and downloaded, all good. Any time after that and the error appears.
As usual, we’re unable to reproduce the issue 
Tested 5 times the link and it worked without any crash. Do you see the Save As dialog box before the “invalid pointer operation” error?
Sorry I seem to be a problem:)
Next time it happens, will try and gather more info.