pdfs sync but references did not, two computers, using Google Drive storage
(using Stand Alone on a Mac). I grabbed nine references and their pdf files on the work computer where my Zotero storage is on a Google Drive. This generally works just fine and new references appear on my other two computers when I open Zotero. But this time none of those references appear in my Zotero window, however they all seem to be there in the "Storage" folder on my Google drive! How odd!
Putting your entire Zotero data directory in a syncing folder (if that's what you're doing) can easily lead to a corrupted database as well as other, less easily traceable problems. You can do it, but you'll get no support for any problems you have with Zotero, as the assumption will - usually correctly - be that they're caused by this.
There are a bunch of other ways, ranging from paying for storage, using a third party (or your own) WebDav, using symlinks for your storage director to using "link https://zotpad.uservoice.com/knowledgebase/articles/103395-what-is-a-symbolic-link-and-why-should-i-use-one-w , using "link to file," potentially in combination with relative links. if I understand correctly the files are synced, but the references aren't. That's exactly the types of problems we'd expect to see with (what I think is) your set-up and the first indication that you're on your way to mess up your database. The files in storage mean absolutely nothing for Zotero without a corresponding entry in the database and there is no way to import them, no.