Folks at VMWare have been reporting a similar issue since the update to 10.14.4 due to a bug Apple introduced in handling large files, have a look at the following link for more details: https://planetvm.net/blog/?p=67185 It's been reported as officially solved by VMWare with Apple's macOS 10.14.6 supplemental update. It remains to been seen if the same applies to Parallels as they haven't been forthcoming about this issue in any shape or form (as far as I know). In other posts, some users claimed that the 10.14.6 supplemental update fixes the issue. Others have reported that macOS Catalina 10.15 still have the issue so I'm still inclined to stay with Parallels Desktop 14.1.3 on macOS 10.14.3 for the time being. I'm thinking of moving to VMWare Fusion, I might not like the UI and integration as much as Parallels but at least they seem to know what's going on with their product and even though they didn't know the solution at first, they were transparent about it. Wish I could say the same for Parallels but it feels more like a case of "you're holding it wrong" to me. Any brave souls willing to try the 10.14.6 supplemental update and let us know how it goes with a large VM?