I have been uploading videos with no problems. I was able to add cards and other features. Then suddenly youtube is saying my video doesnt meet the requirements to add the additional features and needs to be a specific size. I havent changed any settings. Also I cant find any features that restores back to original settings.
It's possible that some specific features on YouTube have restrictions that others don't but that's a question that you'd have to ask YouTube. It's not something we can advise you on, I'm afraid.