May i know how exactly to replicate this? It would be best if you can provide us with some steps or more screenshot on how to replicate this issues locally.
Submit a post with a non-default category ( it is "DO NOT USE" on my site.). log in as admin and view the post for approval. It will say its" DO NOT USE" and when you click on it to edit /view it, the category at the top will say "DO NOT USE" even though thats not selected.
It seems that there are issues on our end. I have created a ticket and it will be included on our next release version. By the way, maybe you can try to apply attached file at this path administrator/components/com_easyblog/includes/composer/composer.php and see how it goes