Navigation Block shows wrong menu

I’ve created a FSE child theme and when I activate it on my live site the menus have to be re-chosen. When I choose my main menu (of site’s main categories) and save it shows my site’s list of pages instead, which I believe is the default WP menu. I’ve tried replacing the header completely with a new saved navigation block with the main menu but the results are the same. The menu shows correctly in the block editor but shows incorrectly on the public side. Screenshots: https://www.dropbox.com/s/xuio3rfow5bq11e/Screen%20Shot%202023-04-27%20at%201.26.58%20PM.png?dl=0

https://www.dropbox.com/s/15wep3lwhwb5m8b/Screen%20Shot%202023-04-27%20at%201.25.59%20PM.png?dl=0

I’m totally confused as to why this is happening and would greatly appreciate any help in fixing this issue.