It's a known bug in Steemit’s code at the moment. If you use all five possible tags, then your post will only appear on the first tag’s list, but not in the following four tags’ categories. If you only use four tags, your post will appear in all of the four tags’ lists on Steemit. It’s a known bug and it’s being worked upon. Until it’s fixed, however, it’s recommended to only use 4 tags out of 5, to increase the exposure on Steemit.
I hope it answers your question.
Perfect explanation. Upvoted. Thank you.