hi schabulsky, i don’t really understand about issue you having. but its working on my side.
take a look at this video : http://d.pr/v/0DIMY
as i know, other themes also do the same (for example newspaper they even force you to use only ID, you don’t have option to show dropdown).
Previously we have feature to load them all, for website that having 1000++ tag, it will crash their site.
Please check if you really enter a tag content, not category. because on your screenshot sport is a category.
also you don’t need to enter the whole word, you just need to enter 3 character to show tag related to those character.