What version of VP is now being used? That's shown at start up and at the bottom-left of the VP screen. If it's been less than six-months since initial purchase, updates are free. No need to pay again.
Try exporting to AVI format, using the MPEG4 compressor. Try exporting at a lower resolution. Other than that, there's little more to suggest than what was requested in your Sept. 25 post. Please share the project. Someone will check it out and come up with a fix. This can be private via a personal message to me. Click the folder at the top-right of this forum. Just follow these steps...
1. With your project on the timeline, click on MENU at the top-left. Click FILE|BACK UP PROJECT FILES TO FOLDER. Choose a folder and SELECT FOLDER.
2. Locate the saved, numbered folder and upload it to a free server. ( No need to upload the export file or only the VPJ.)
3. Get a shared, public link. If using Google Drive click GET SHAREABLE LINK. Click the blue "Change to anyone with the link..." Then click COPY LINK | DONE.
4. Paste that link here, or click the folder, above top-right in this forum, and message it to me. This is private and won't be shared.
* Before uploading, right-click the folder, click PROPERTIES. Look at the File Size to confirm that it's not too big for the free space on the server.