Issue: Blog tags disappearing

Do mods manually delete tags? If not then there's an issue. After I publish a blog post I'll add a few tags on. These save at the time and appear in my blog tag cloud and link to the correct post when clicked. However, when I log in the next day or day after some of the tags have disappeared from their individual posts and from the tag cloud. I've tried replacing them and same as before, they'll save at the time only to disappear the next day.

It seems to be the same bunch of tags disappearing so I'll list them below to see if you can spot anything wrong with them. They come from several different blog posts.

ougi yuzuha, akanai tobira, bukiyou na silent, cute devil, kawaii akuma, darling, endless world, ichigenme