Hello,
- don´t use dev-versions from github which are currently under development. they can break any time
- use the official app store versions
- the mentioned error is not related to non-playing files. its something which is being fixed in core (https://github.com/owncloud/core/issues/22370#issuecomment-264699753) but does not prevent songs from playing
- there has to be another issue somewhere e.g. a broken audio file
- for any issues, please use the git-issue tracker
thank you,
Rello