I used to be able to search my own store by tags by simply typing in the tag (eg "paperback" or "poetry"). Now that's no longer possible, I have to open up the filter options and select the tag, if it even shows up (it seems to limit options to only the most popular). This is super inconvenient and I'm not sure what problem it's trying to solve.

If Pango wants to let people search by just the title or author, a better way would be to have advanced search fields in the filter options that let the user opt in to just searching those fields—but it should be an advanced feature, not the default.