Report ID 769733682 (Syncing Error)
I do not know what triggered this, but I'm getting the red exclamation point when I attempt to sync my Zotero database. It says, "Item data not loaded and field '1' not set for item 1/9SJXV2UJ," and tells me to report the error.
You should also just restart Zotero and try again, if you haven't.