Upon deletion of Guest Author, Linked Posts are not transferred

Hello,
we have some guest authors who have now joined full-time and to accommodate their older posts. I have created a new author role and linked the guest author, but since there is an indexation issue with Yoast and Co-Author Plus we decided to make a new Author with the same name.

While deleting the Guest Author from Co-Author, it asks if the posts should be moved to the linked author. Upon using that option, it fails to link the posts to the linked author.

This is a serious issue and needs to be looked at on priority.

Please help