Audio [Q] Walkman plays some flac files, but not others

Walkman app plays most flac files fine. I have found a number of flac files that it cannot play. I want to understand why. (edit: Google Music cannot play these files either)

Here is an example file which plays fine on my computer, but fails to play on my Z1:

(sorry, I could not link due to low number of postings) - I will pm the link to anyone interested.

Thank you for any insight!