Synch error message
760041814
[JavaScript Error: "Image corrupt or truncated: " {file: "" line: 0}]
[JavaScript Error: "Name '= Premium Content Log In | Create a Free …' too long" {file: "chrome://zotero/content/xpcom/sync.js" line: 891}]
[JavaScript Error: "Image corrupt or truncated: " {file: "" line: 0}]
[JavaScript Error: "Name '= Premium Content Log In | Create a Free …' too long" {file: "chrome://zotero/content/xpcom/sync.js" line: 891}]
"Name '= Premium Content Log In | Create a Free …'
search for that - might be a tag or an author name or so - shorten it or delete the item in question, empty the Zotero trash and try syncing again.
Searching just on "Premium Content Log In" turns up dozens of hits.
What to do next?
Do they all have that in the author field?
But yes, it sounds like you may have to edit the author field for each of the items.