TV Show title appearing as FM65UH~Z

Hi there.

I’m having a problem with the metadata for a TV show. The main title for Foo Fighters Sonic Highways shows up as FM65UH~Z. But selecting it displays the all episodes with proper metadata.

I have successfully edited metadata for plenty of other shows, but this one’s different. Am I doing something wrong or is it a bug?

Media library is stored on WD My Cloud 4TB if that makes any difference.

Same thing happens on ATV4, iPhone and iPad all running 4.1.1.

Images attached.