If the Blog Posts block isn't displaying your custom post type, you can try the following troubleshooting steps:

Check Block Settings

Ensure that the Blog Posts block settings are configured correctly to include your custom post type. When adding the Blog Posts block, there should be an option to select which post types to display. Double-check that your custom post type is selected.

Custom Post Type Support

Verify that your custom post type has support for the show_in_rest parameter set to true. This parameter enables the post type to be queried via the REST API, which is necessary for the Block Editor to retrieve and display the posts. You can check this parameter in the code where you register your custom post type.

Permalink Structure

Make sure your custom post type has a permalink structure defined. If the permalink structure is not set or conflicts with the default WordPress structure, it might affect the visibility of posts in the Block Editor. You can set the permalink structure when registering the custom post type or by updating the permalink settings in WordPress.

Flush Rewrite Rules

Sometimes, changes to post types or permalink structures may require flushing the rewrite rules to take effect. You can do this by visiting the "Settings" > "Permalinks" page in your WordPress admin panel and simply clicking the "Save Changes" button. This action refreshes the rewrite rules.

Plugin or Theme Conflict

Deactivate all plugins except for the ones essential for WordPress functionality and switch to a default WordPress theme like Twenty Twenty-One. Then, check if the Blog Posts block displays your custom post type. If it does, reactivate each plugin/theme one by one to identify the conflicting element.

Custom Code or Functions

Review any custom code or functions related to your custom post type. Ensure that there are no specific exclusions or limitations set that might prevent the custom post type from appearing in the Blog Posts block.

WordPress Core Update

Ensure that your WordPress core installation is up to date. Sometimes, issues with custom post types not appearing in blocks are resolved with WordPress updates that include bug fixes or improvements.