We use coauthors plus (via VIP) for bylines. We have few post creators and tens of contributors. The post creators have WP login, and contributors don't. Typically, a post creator would create a post and put a contributor's name in byline.
Exa: Jim is a WP user and John is a contributor. John wil email his story to Jim and Jim will log in to WP, create a post and assign it to John's name via byline. So when you view the post you should see John's name in byline, not Jim's - Jim is just a silent worker who takes copies from contributors and post stories on their behalf.
However, when you view the post, the byline says "By Jim and John". When you edit the post, strangely, both Jim and John's names are there in the author's field. Once you remove Jim's name, everything is back to normal.
Could explain why it is doing this and what we could be doing wrong?
Happy to show you the code