I am having these exact same problems. Out of curiosity, which theme are you using? I fear that it may not be able to find my theme because it pulls the sidebar in the code before it pulls the main page code, meaning it only indexes posts and categories directly linked in the sidebar. While it’s rare, I think I may be running into Googlebot’s character limits.
Thanks! I actually have been troubleshooting and found it was some italics in one post. I’ve taken them out and it fixed everything.