Stuck on Level 7 ... How should I work this?

As you thought, this is not a bug. Here are a few options available:

  1. Change your lesson order in settings to shuffled (I wouldn’t really recommend this).
  2. Do your vocab lessons from the previous level more quickly. You could do this if the vocab is relatively easy for you, but if that’s not the case you might get overwhelmed.
  3. Use the [Userscript] WaniKani Lesson Filter script. This will allow you to learn radicals, kanji, and vocab all together during lessons. This way you can keep progressing while still learning your vocab. If you try this, just make sure you do around 3 times more vocab than kanji (when available), or you might get behind on your vocab lessons. You could also use this to do all your radical lessons right away if you wanted to.