One Cat Not Showing

I successfully set up a redirect from my ‘categories” to a “Page” that will be my silo Category. When I switched to stackable > Posts Blocks, all my posts from different categories showed up. I’m unable to show only the posts that belong to that category.
When I go to “Document tab” > Parent Page: One category page doesn’t show up. At the moment, I only have two categories. I totally miffed as to why one shows up and the other doesn’t when in the Document > Parent Page dropdown.
I have to go back to the previous blocks I used where I had no problem.