Co-author add-on or remove disappeared with WordPress 4.1

Hi there.
Following a recent upgrade of WordPress to 4.1.1, which could not be delayed for important functional reasons, the co-author plug in is no longer working. The post field where a user can add or remove a guest author does not work. No possibility to change, add or remove anything. I read that the latest version of Co-authors plugin has not been tested with the latest version of WordPress. Can you help with a work around? It is rather urgent, as we are publishing scientific papers whose authors and co-authors must show their names for indexing and financial reasons.

When will the latest co-author plug in version be tested and cleared for WordPress 4.1.1.?

Thank you for your support.

https://wordpress.org/plugins/co-authors-plus/