when importing a PSE-12-catalog (>10.000 fotos, a few videos) to LR CC 2015 test version the import stops at 2000 fotos with an unknown error. I already repaired and optimized the PSE-catalog with the catalog manager-tool.
Another catalog (about 5000 fotos) could be imported without problems.
Thanks for having helpful ideas!
(iMac, MacOS Sierra, Fusion Drive 1TB, 8 GB RAM)