It took me a while to figure this out, truly one of the most irritating bugs in Zoho. I hope you find this information helpful.

When using the knowledge base to create articles, make sure your keywords are in lowercase and separated by commas. Otherwise, if you try to reuse these keywords as tags (to copy paste and save time) then the article won't save, Zoho will not tell you why it just says: "Article couldn't be updated."