I decided to sync all my attachments to Zotero servers -- about 7-8 GB in uncompressed form. So I bought 10 GB and started the sync. It ran for a little while (maybe 30 minutes) and stopped with no error message, but it had only uploaded 1.68 GB. Checking some items at random, it appears that many attachments are now on synced to the Zotero server but many are not -- I don't see a pattern to it. Any thoughts?