It's a UI bug, you can type out the tag you're wanting to enter somewhere else, ctrl + c, and ctrl + v in that input field so you don't accidentally mistype.
Also, there is a bug on the name lenght validation, if i put 5 character it says that the name must be between 6 and 30 char.. but if i put a name with 6 char it says it can't be longer than 30