I'm having real problems syncing my desktop (windows 10) with my online library. Trying to use Zotero to manage ~15,000 references for a meta analysis so was wondering if it's something to do with the size of the library? However also finding that the online version isn't allowing me to more references from one collection in the group library into another?

I've tired all the usual restarting etc and was wondering if anyone had any ideas?