Why isn't my literary agent query working?

About to query a literary agent? Or are you receiving rejection after rejection? It might be your pitch!

In this video, literary agents Jessica Faust and James McGowan discuss their top 10 reasons why agent queries often fail, and how to fix them!

I originally came across this video via Pub Tips subreddit; specifically this post.

The same post also summarises the above video with these tips (although the original video is still worth a watch!):

1. Query is too long and doesn't get to the point.
2. Query is too short and doesn't describe the book.
3. Query talks about themes too much instead of character / plot.
4. The genre is marked wrong.
5. Your word count is wrong.
6. Query's voice / tone doesn't match the expected voice / tone of the book.
7. For non-fiction - the author doesn't show their platform / credentials. For fiction - the author doesn't look professional / taking it seriously.
8. The query is rude. Dissing the genre, insulting the agent, passive-aggressiveness.
9. Query is sent to the wrong agent - one who doesn't represent that genre / isn't taking this type of the book.
10. The query isn't the problem, but the book is.