The app shows that a MusicXML file assigned is not readable, what can I do?
The problem is probably related to an outdated format of the file. You may have a view into the XML file and see if at least MusicXML 3.0 is set on the corresponding tag as Play ‚n‘ Practice supports MusicXML 3.x.
Also Play ‚n‘ Practice requires MusicXML files to provide the extension „.mxl“ for compressed and „.musicxml“ for non compressed files.
You may try a conversion of the files to MusicXML V3 required via the MuseScore score editor app available for Mac and for Windows or any other notation app capable of converting MusicXML files.