AFAIK, it may need to verify game files, maybe download one or two additional small files (which I thinks is the specific manifest) and be good to go. Another thing I'm reading just on a brief search is you can find the games steam id and then modify the appmanifest_####.acf file to read-only to prevent any further updates if the option does not appear in properties. Good luck, and don't give up hope!

Edit to add: the commenter who gave this bit of info also rightly noted you should back up your game files if you have the disk space to do so