That was the problem. I made a post and attached all my categories to it. All categories now show up in the drop down for the post grid query. Thank you!
Here’s my list of categories, I have 26: https://upfied.com/wp-content/uploads/2020/05/category-page.jpg
I’m trying to display post from each category on it’s own page. I create the page, add the block for a post grid, but when I try to select a certain category, I only have 3 to choose from: https://upfied.com/wp-content/uploads/2020/05/query-category-dropdown.jpg
