Yep, tags seem to be... kinda broken, unfortunately Dunno, every time I tried to search for one of the tags I put under the episodes of my own comic, I couldn't find it for the life of me. The only tags that seem to work are the ones you put on your whole series, rather than individual episodes... which is a shame, since it'd be an awesome way to find stories.
...Also, spaces in tags don't work. They get automatically changed into underscores and, if you want to be able to find your tag, you have to manually type the underscores in it. So like, if you have "urban fantasy" as one of your tags, people would have to type urban_fantasy to find it. Makes me wonder how many series won't show up in tags because Tapas never made it clear how to search for a tag...