Can’t link a parent page to the custom post

Do you have 2 or more published posts within this post type to work with? I’ve found that you can’t publish a post as a child of a non-published post for the parent.

Yes, I have a lot of published posts of this type, so that’s not the problem.

Can you copy/paste over the blob of text on the right hand side when you visit the “Tools” menu item and the “post types” tab? I can review the settings used there for you and see if anything stands out. I’ll also be able to import what you have configured into a local install and test therre.

Otherwise, I’m not sure what’s going on and why you’re not seeing the option.

This is the content you can use to install my post types:
{"activity":{"name":"activity","label":"Activiteiten","singular_label":"Activiteit","description":"","public":"true","publicly_queryable":"true","show_ui":"true","show_in_nav_menus":"true","delete_with_user":"false","show_in_rest":"true","rest_base":"","rest_controller_class":"","has_archive":"true","has_archive_string":"","exclude_from_search":"false","capability_type":"","hierarchical":"true","rewrite":"true","rewrite_slug":"","rewrite_withfront":"true","query_var":"true","query_var_slug":"","menu_position":"","show_in_menu":"true","show_in_menu_string":"","menu_icon":"","supports":["title","editor","thumbnail","excerpt","trackbacks","custom-fields","page-attributes","post-formats"],"taxonomies":["category"],"labels":{"menu_name":"Activity","all_items":"All Activities","add_new":"","add_new_item":"","edit_item":"","new_item":"","view_item":"","view_items":"","search_items":"","not_found":"","not_found_in_trash":"","parent_item_colon":"","featured_image":"","set_featured_image":"","remove_featured_image":"","use_featured_image":"","archives":"","insert_into_item":"","uploaded_to_this_item":"","filter_items_list":"","items_list_navigation":"","items_list":"","attributes":"","name_admin_bar":"","item_published":"","item_published_privately":"","item_reverted_to_draft":"","item_scheduled":"","item_updated":""},"custom_supports":"all"},"activity_archive":{"name":"activity_archive","label":"Activities Archive","singular_label":"Activity Archive","description":"","public":"true","publicly_queryable":"true","show_ui":"true","show_in_nav_menus":"true","delete_with_user":"false","show_in_rest":"true","rest_base":"","rest_controller_class":"","has_archive":"true","has_archive_string":"","exclude_from_search":"false","capability_type":"post","hierarchical":"false","rewrite":"true","rewrite_slug":"concertdatabank","rewrite_withfront":"true","query_var":"true","query_var_slug":"","menu_position":"","show_in_menu":"true","show_in_menu_string":"","menu_icon":"dashicons-archive","supports":["title","editor","thumbnail"],"taxonomies":[],"labels":{"menu_name":"","all_items":"","add_new":"","add_new_item":"","edit_item":"","new_item":"","view_item":"","view_items":"","search_items":"","not_found":"","not_found_in_trash":"","parent_item_colon":"","featured_image":"","set_featured_image":"","remove_featured_image":"","use_featured_image":"","archives":"","insert_into_item":"","uploaded_to_this_item":"","filter_items_list":"","items_list_navigation":"","items_list":"","attributes":"","name_admin_bar":"","item_published":"","item_published_privately":"","item_reverted_to_draft":"","item_scheduled":"","item_updated":""},"custom_supports":"all"}}

It is about post type ‘activity’.

Not a whole lot standing out overall and I was able to assign parent posts right away after import.

https://cloudup.com/co1ANTGXa_8

I added a post and named it “Activity One” and then added a second post named “Activity Two” and the dropdown in the screenshot there showed up during the editing of “Activity Two” with the first post available to select.

Is this not what you’re seeing?

Also just in case, are you trying to associate “activity” post type with “activity_archive” in a similar fashion?