www.makemkv.com

I just purchased the BP50NB40 NB52 model this month and have exact same behavior as @subduedcarrot after the upgrade. His screen shot info is also identical to mine. Only difference is the mfr date on my device is April 2026.

I had followed the initial firmware update steps very carefully, then ...

Here is a site page which is selling one company's Audio-only blu-rays:

http://www.musicdirect.com/c-805-blu-ra ... -disc.aspx

There are also a few other smaller companies that manufacture BR Audio only discs, if I recall correctly.