Hi,
Nice Catch, great app.

wma support on your phone is almost certainly because the Huawei music app uses its own codecs which are separate from the Android system.

This tiny app will show you the codecs which are supported directly by your phone:
https://play.google.com/store/apps/details?id=com.crayonio.mediacodecquery

Yes !

But does the device itself list WMA as a natively supported format?

Installed MMA for the first time, after scanning my music files on sdcard it ommited all .wma files.

MMA 1.3.1.0712 , android 7.0 on a Huawei mate9.

-the native music player *does* index and play .wma files, so this is a MMA issue.