Post Author corrupted

Hi,
after adding [posts-by-tag tags = “XYZ”] to a post the author at the end of the post (entry-meta-bar) is not correct anymore. It get replaced by the author of the last entry in the list generated by the ‘Posts By Tag’ plugin.
When I remove the post-by-tags shortcode wordpress shows the right author again.

I am using wordpress 3.9 and the attidude pro theme.
thank you!

https://ww.wp.xz.cn/plugins/posts-by-tag/