But did you start the project on this version? If not, then the problem could have occurred before upgrade, which cannot fix a damaged project.
Do you mind elaborating on what what this note means?
Did you ever get a warning dialog upon opening the project that some files are missing or it needed repair? If so, and proxy was on, then it would replace the source clips with the proxy. So, at export time, it is unable to replace the proxy with the source because it lost track of it.
Turn off proxy, go to the clip you think has a problem. Check the filename in Properties. Is it correct? If not, to fix it:
- Open the correct source clip in the Source player
- Set the in point to what you used before or want now.
- right click the timeline clip and choose Replace.