Attachments not working on Mail

For some reason attachments within emails are not working, it seems to be random, although I'm sure there is a pattern, but most of the attachments that people are sending me download, I can see the icon and the bar loading up, but when I go to drag to desktop, or save, nothing happens. Also when I close the message and go back to it, the attachment has disappeared.

My only work-around is to forward it from my phone to my Gmail account, (also in Mail) and this works.

It's really annoying, and making it very hard to work on.