Audio Fade Changing When Re-Opening file

Hi all, this problem appeared two days ago and I haven't been able to find a solution; any advice or ideas would be much appreciated as this is driving me crazy.

The problem: I want a section of audio to fade in, say, so I put in the nessicary keyframes and I get a linear fade between the two points, which is what I want. 

I save and close the file. But when I re-open it the same fade looks like this, even though none of the settings I can find have been changed and it's still identified as the linear option.

I've tried compensating for it with the other options but that proved tedious and the results not great, espcially on a large project with a large number of little volume adjustments. I've scoured the program looking for a setting that could've changed (I have, however, only been using P. Elements a few months so could've easily missed something). I've tried uninstalling and reinstalling the program but that changed nothing. 

Any ideas or potential workarounds would be very much appreciated.