Sync from Lightroom Cloud into Classic stuck and no longer working

I was using LR cloud mainly but now I am enteringo into more serious photography and I want to make use of map, print and book modules of LR Classic. So I've activated the sync feature to get everything on LR Cloud into LR Classic and work with those modules from there. The sync gets stuck in the middle. I have around 34,000 photographs on LR Cloud and when I get to sort of 13,000 on LR Classic I it gets stuck. No error, but no progress. I had some sync issus detected on LR Web which I solved but the sync continues to get stuck. I rebuild the sync data twice to no avail. I'd really like the cohesiveness of the LR Classic workflow, allowing you to play with collections to print, build books, and also the map, but I cannot get all the cloud pictures to get downloaded. 

I want to add that I have around 146Gb of photos on the cloud and I am working on a brand new laptop with a 1Tb SDD drive, so I do have plenty of spare disk space to get all the cloud photos into classic.

Any ideas to sort this out are welcome!

Best regards,

Guillermo.