The styles play properly in the main window. The problem is limited to auditioning in the style picker. I investigated further and I can audition if I use the Play button for "Play Using Current Chordsheet for song".

What doesn't work: double-clicking the style; pressing the spacebar; clicking the green play button icon for the premade demo.

So now BIAB cannot play the WMA demo files, but it could before I updated. I can play the WMA files outside of BIAB. I updated to 607 around the same time that Windows 10 did a mandatory update, so it may not be entirely a BIAB problem.