How do I How to copy AI-generated captions from one project to a new project?

The original track was 8 minutes and 34 seconds and about 1 minute went missing midway through making the video.

I need to replace it using the track which is intact from a good back up project. 

I have tried Copy the track and it won't copy between projects. 

What can I do please to import the non-corrupted AI-generated caption track between projects?