How long is the project? What is the resolution of the bulk of the source files?
Have you tried an AVI export, using the MPEG4 compressor?
This needs to be seen by folks here. Please upload the project, or a portion that contains the zoom. Of course. Save Project File AS before doing any excising, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. Then you can restore a project to the state it was in when saved. Just double-click the VPJ file (which isn't playable).
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 - Google Drive, MS OneDrive, etc.* (Don't 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.