About the only way to pin this down, Julie, is to upload and share the project files as instructed above. It's not likely a codec or parameter.
A new version will be released shortly but it will have some incompatibilities with the old, owing to programming changes. Use that version for your next project, if possible. For licensed users upgrades are free for up to six months. After that, VP will continue to fully function but a fee will be required in order to register the latest.