Preview result 404 BUT VIEW Page displays page

Hi Support-Team,

unfortunately we can't figure out, why

Preview results is 404 error

BUT

VIEW Page displays the page. Attached below screenshot.

NOTE:
CustomPress is activated on aboutme.bestof.... sub domain
Acutually settings are only done for Self-Introduction (My Turn) page and posts to get familiar with this amazing WPMU Dev plugin.

Support Access is granted.

We appreciate if one of you expert can help to sort this out.
Thank you.
Prinz