Mac Mini as a music server

Do you think it stems from Apple's penchant for not providing ancillary vendors pre-knowledge of impending changes/updates & the subsequent lag as the ancillary vendor "catches up" to make their program compatible?

Yes, absolutely. Over the years each and every music player program I've used has been impacted by an Apple update. (I have licences for Amarra, Audirvana+, BitPerfect, Fidelia, HQPlayer, JRMC, and Pure Music.) Very frustrating indeed. From my experience HQPlayer has seen fewer issues than the others. Eventually the problems get fixed, for the most part anyway. I stopped using Pure Music entirely after one such update .. the problem was never resolved and I gave up. Don't even get me started on Amarra!

Of course the easy option is, as @thaluza mentioned, to turn off auto updates but I'm with @sbank on this one. 

I've been running Roon on my 2012 mini for about 5 years. It feeds an Allo USBridge in another room which in turn feeds my NuPrime integrated. I haven't bothered to update the OS in quite some time. I use it strictly as a music server. It is always on and functions beautifully. Everything sounds great. I'm actually considering buying another one now to have ready when this one inevitably dies. 

I have just replaced my Pono that was driving Hegel integrated amp with an Auralic Vega DAC.

I have built Mac Mini i7 quad core with internal SSD & external firewire 800 SSD and got all audio in FLAC form on the Mac Mini.

I got JRiver MC25 working on the Mac Min with the library etc.  All is working great so far.

Now I get remote shutdown working with Mac Mini in headless config with the Mac Mini tucked behind all the stereo stuff.

Now I get MC25 installed on Win laptop and get server/client config so that I can see the Mac Mini library etc.

All seems good until I try to control the Mac Mini server remotely from the win machine.  I can pick things from the library, but MC app architecture seems to be to 'suck' the data from the server and pipe to an O/P device connected to the win machine.  Bummer!  Why would I want to pull the hi res audio from the server and pipe it to a 'toy' of a dac? 

I can't even understand the reasoning of the design.  One invests a few $k in a stereo; where does the idea of this kind of network transmission of digital streaming of data fit in with that?

Just getting a wired connection direct to DAC to faithfully keep up with 24/192 audio is enough of an issue for the Mac Mini. I'd like to see it stream bit-perfect at 24/192, but it's not quite there.

I haven't bought JRiver MC25 yet, I'm on a 'trial' period.  I'm a little disillusioned at this architecture though.

My vision is to have remote Select; Play; Start/Stop; Access to Supporting data of the Mac Mini sending digital audio direct to its wired DAC connection.

I think the JR MC UI has good potential to satisfy these aspects, but the design does not seem to be there to support the desired function.

I know I can do screen share from Mac to Win client using VNC, etc.  That just seems like adding more unnecessary work on to the Mac Mini.

Is JR MC simply the wrong app for what I want?  What else should I look at?