The problem is a checked 'Include Render Files' I believe.
So I have done a bit more work and the following seems to be true. I was trying to duplicate two different projects from a mobile drive (USB 3) to my long term storage 6TB Thunderbolt drive. Every time I tried to duplicate the project I would get lots of stuff placed on my internal SSD drive and eventually it would run out of memory and FCPX would stop/crash.
Today, I tried doing the 'Dupllicate Project' on both of these project BUT, I unchecked 'Include Render Files' In both cases, the duplication process has not written any files to my internal SSD and it has gone very smoothly! At the end of the duplication, I close FCPX, disconnect the mobile drive, and restart FCPX. Rendering of the duplicated project begins and it takes a few minutes depending on length of the movie, but once done, it seems to be retained.
So if there is a bug it is related to the routines effected by the 'Include Render Files'.
I have discovered another nasty little thing with FCPX file management. This issue was discussed elsewhere on the board, but I thought I would mention it again in the hopes perhaps there is something I don't understand.
If one imports video files they are stored in the Original Media folder in the FCP Events folder and when you duplicate the project to another drive they are appropriately copied over.
BUT, if you drag and drop the video files from an Aperture Library into an FCPX events, a file is created that references the video file. In preferences the "Copy file" is checked. If you do a consolidation of project, FCP says everything is there and the reference files in the Original Media folder remain as references files pointing to the file in the Aperture Library.
WORSE, when you duplicate the project to a new drive, it duplicates the reference files (and not the actual media) so when the parent drive is offline, those reference files can NOT find the original video media and you get a missing clip report.
This is certainly not the way I would have expected a duplicate/consolidate functions to work. I have solved the problem manually by going to the Aperture library and exporting the video files (making sure there is no change in the file name) and then using those video files to replace the reference files in duplicated project's original media folder. Once all of the complete video files are in the Original Media Folder in Events, the Duplication seems to move everything over properly.
There does not appear to be a method to drag and drop video from Aperture and have the original media folder in events to actually contain the video file rather than some referencing file. At least the user should have a choice to actually copy the video or leave it as referenced.
The only working solution is to export the video from Aperture to a temporary folder and then import it into FCPX at the time one starts working on the project. It is an extra step, but in the end, when you want to move the projects to new drives at least it will have all the necessary date.
I don't use the photo browser. I just drag/drop from Aperture (video and photos) into either the event folder or for photos, the timeline. Photos work fine, video has this funny referencing strategy.
As a photographer who likes to create fusion documents (video + photographs) using multi-cameras, it is very useful to have all the video/stills in Aperture. Once imported into Aperture, I can correct the time stamps and then display the video/photographs by date so they are in reasonable sequence.
BUT, FCPX is the prefered approach to combining the two in terms of a final video file while Aperture is excellent at getting the stills to where I want them.
If I drag/drop and its referenced, that is fine, but there should be a mechanism for me to consolidate all of the original files into a single structure.
The FCPx team could take some lessons from the Aperture team, IMHO.
I drag/drop from the browser view.
I need the time stamp to align with the pictures so I think Aperture is a better location of this, although I have not explored the issue within FCP.
I find the Aperture file structure much easier to understand and work with, but I am still learning the quirks of FCP. Perhaps once I have mastered the quirky behavior of FCP, it will be ok as well.