First of all, there is no stress as I solved this by creating a backup file. So treat this as more of a notification or oddity than anything else.

In one of my projects which has mulitple different file types, framerates, and a fair amount of effects including zoom, stabilization, crossfades, speed etc., I found after export that there were some sections missing. I went back in and there's no problem in preview so I export again. This time there are different sections missing. *scratches head*

So I assume it's an export problem and try a different file type (mp4 - avi). Still random bits of the video just being blank (but this time some parts were with text over them and the text came through fine)

Then I start noticing that the preview images and some of the files in the editor were blank. As in, the section of the file was still in the program there, but there's no image in the preview. So I fiddle around for a while, open and close, save, resave, reimport files and figure out that if I reset the frames they appear again (briefly). But then they disappear again once i've played with another file. I tried to find a common effect but there didn't seem to be one. Files with no effects were just showing blank (audio, text seemed unaffected).

At this point I'm getting frustrated and worried because this was a project for work that I'd spent  weeks on and I had a deadline. As a last resort I saved a backup and all associated files on a different drive. Opened it up and it works perfectly. exported the file and we're all good. But if I go back into the original one, it still does this random dissappearing act. I run other project files off the same drive so there's no issue with the drive. The raw files aren't corrupt because if they were the backup wouldn't have fixed it. I didn't change any setting between original and backup files... I've not had any other project file do this...

Anyone have any ideas? To me it sounds like some problem when Magix goes and fetches the file but I have no idea what. 

If you're curious I can do a screen capture and upload to youtube.