I’m having the same issue. I will switch to PublishPress soon (60€) which has acquired and incorporated the Plugin Bylines.io, which was made by on of the authors of Co-Authors Plus.
Co-Authors Plus itself hasn’t been updated for several months and many of its bugs have been fixed in the development of Bylines and then in PublishPress.
I will let you know if switching to PublishPress has solved this bug for me.
Hi, I have tested PublishPress for about two weeks now and can confirm that this bug has not happened again since.
After switching to PublishPress, I only had to do some minor changes since the plugin is based on the code of Co-Authors Plus. The template tags are well documented so switching to PublishPress was easy.
I hope this helps!