Displaying and editing post's tags works wrong

Generally there is a difference between Denser and Condenser with displaying the first tag.
Repeat steps:

1. Create post with spam tag.
2. The Spam tag (first tag) is not displayed in the tag list but is visible in the author category.
3. Click Edit post and delete spam tag and type the new test tag.
4. The test tag should be visible on the tag list in the post (no tag is displayed in Denser but in Condenser test is displayed).
5. Click again Edit post and tags spam test should be visible into the tag input.

In Denser the first tag is not always shown in the input tag during editing the post.
Second example:

1. Create post with tags test one two three.
2. One two three should be visible on the tag list in the post.
3. Click Edit post and delete tag test from the tags input in the post editor.
4. There should be visible one two three in the tag list but there is only two three in Denser.