It's not that, it's just some of the developers have been on vacation lately and they're also working on releasing a build of Media Center 21 for the Mac, so these things take time. Even though there's no official response yet, Jim (JRiver's CEO) reads every post on these forums.
Thank your for your reply. I feel more confident that my issues will eventually be addressed. This problem occurs every time for me, and it looks like for others, as well. There's nothing arcane about my Mini. It was bought new March 2015 and is running the latest Yosemite. I bought to use strictly as a media server. There's hardly anything running on it, apart from MC, Firefox, and OS X mail.
While I have your ear - MC frequently crashes on my machine, even when MC is seemingly doing nothing. E.g., it starts automagically when my machine comes up in the morning and I find the message box that MC crashed sometime during the day. In the case where I haven't been on the machine but I know that MC was running successfully for a least awhile, because I peeked, it's especially mysterious. I suspect TimeMachine may be implicated.
Also, I ripped 3 CDs in a row and MC crashed. WTF?
This isn't my first rodeo. I have a PC, a MAC mini, and a Raspberry Pi (running Debian Wheezy), all running MC. All connected to a Synology NAS, where my media files reside. The Windows machine is, as one might expect, completely stable. OS X has it's problems. On the Pi, MC comes up and completely freezes, but that's a discussion for another time and forum.
I tried using PowerDVD on the PC and returned it for the 30 day money back guarantee once I discovered MC. While PowerDVD did do the job, I found its interface very 1990's and its video scraper a joke. Kudos to whoever conceived MC's video scraper. For info and cover art, not only does it give one the choice of several like named movies with their respective years, but if that is not sufficient one can choose from different data bases. Very cool. It was the only scraper that could resolve the Korean movie 'Killers". All others gave me the Ashton Kuchin version. To PowerDVD's credit they gave me a full refund.
For what its worth, I used to use Plex, with the server on my PC and the front end accessed through a Roku channel. Completely free. However Plex doesn't handle 1080 very well and I had my suspicions about its 7.1 support.
For what it's worth, my media needs are currently being met by Kodi, running 24/7, headless on the Pi using OpenElec OS. I use one of the many available iOS apps to control it. Movies output to my Onyko through HDMI. Music travels thru a HiFiBerry to RCA inputs on the Onkyo. Kodi's front end is primitive, somewhat obscure and baffling, and completely frustrating, but its back end is rock solid. It runs forever and plays everything I give it, all for free.
Having said all this MC is completely superior. Interface, abilities, features, and sonic and visual reproduction are head and shoulders above all other offerings. Definitely, the one to purchase, in spite of a few warts.
Nice job.