When we were having our save issues with our older hardware, the save
would start, run for quite awhile, and then abort. You may be running in
to a similar issue since adding the image catalogs back in to your save
may significantly increase your save time.
Speaking as someone who created a system with just the base OS on a 2.7TB
machine which made it 0.23% full. Created four huge image catalog entries
to fill it up (write over disk space to prepare for sale) and then deleted
these four image catalogs and got it back down to 0.24% full.