Sync problem after moving to a new PC

I have just got a new netbook to replace the one I was using, which has become a bit slow. Both are Asus machines and both run under Win10-64bit with all the updates.
I have to libraries, let me called them L1 and L2. L1 is small, L2 is a bit less than 2Gb. After copying all the files in the new PC and installing seafile client 7.0.1 (same version on the two netbooks) I could synchronize L1 without problems but L2 keeps showing “initializing”, for hours! I have even tried to remove the local folder, after de-syncing of course, suspecting some possible conflicts. But again, after syncing the library I only see “initializing” and nothing is downloaded (files are present on the server). I have no idea how to address this problem. Any hint?
Thank you in advance.