PR #16814 breaks Co-Authors-Plus plugin Guest Author creation functionality

[onpubcom]

Describe the bug
The filter merged in PR #16814 blanks out the default 'Auto Draft' title string for auto-draft status Posts, which leads to breakage when you try to create a new Guest Author with the co-authors-plus plugin.

I was torn as to whether to file this here or via that plugin's repo, but it seems like maybe this filter logic is making some assumptions that might lead to breakage in other plugins that have similar current dependencies on core/default Auto Draft title functionality.

To reproduce
Steps to reproduce the behavior:

1. Install/activate gutenberg 6.3.0 plugin from wordpress.org
2. Install/activate co-authors-plus 3.4 plugin from wordpress.org
3. Go to /wp-admin/post-new.php?post_type=guest-author
4. Attempt to add new Guest Author. The auto-draft post gets created but none of the Guest Author fields are able to be saved properly because of the Co-Authors filter_wp_insert_post_empty_content filter check requires the auto-draft Post's title to be defined in order for it to continue with its other custom Guest Author Post save hooks

Expected behavior
Deactivate the Gutenberg plugin and Co-Authors-Plus Guest Authors are now able to be added/updated properly again.

[onpubcom]

See also:

• Can't create new Guest Authors when latest Gutenberg plugin is installed Automattic/Co-Authors-Plus#702

[onpubcom]

Thanks so much.