Sharing Failed

Hi People

I'm new to FCPX but have successfully shared Master files to my computer from projects.
This is latest project has more files & editing done, meaning it's bigger. But keeps coming up 'FAILEd'
Gets to %39 and stops. Ive tried changing/reducing program etc things around at the point that it has stopped .
I'vbe wAtched some YOutube fix it tuitorials & tried some suggestions.

Can any one help.

MacBook Pro 32Ram
MAC OS Catalina 10.15.4
I have Plenty of Disc space.
FCPX 10.4.8

??

Disable background rendering in FCPX preferences, then delete all render files via File>Delete Generated Library Files>Delete Render Files>All.

Then select all clips in the timeline with CMD+A and do a one-time render with CTRL+R. Observe whether it finishes OK and is playable. If so, then export this way:

File>Share>Master File>Settings, Format: Computer, Video Codec: H.264 Faster Encode, Resolution: 1920x1080.

If that fails, state the error or behavior, also what codec the media files are. You can play the file in Quicktime and do CMD+I to see this.

You can also try making a snapshot duplicate of the project, open that, strip all effects with Edit>Remove Effects, then export that using the above settings. If that works, then make a new snapshot of the original project, select only 1/2 of the timeline clips, do Edit>Remove Effects, render that with CMA+A and CTRL+R, then try to export. Depending on whether that works or fails repeat the process on 1/4 then 1/8 of the timeline until you find what region and what effects are causing the problem.