Phoenix capture not working in El Capitan on brand new trashcan

I have a brand new MacPro (trash can) fresh out of the box and mounted in a Sonnet thunderbolt chassis. The most recent available Phoenix card drivers are installed and Catalyst recognizes the card (it's says "Have Phoenix Card" in the drop down source list) but Catalyst only shows black input for the Phoenix card (PE4).

I've tried both M466 and N561; neither will see the Phoenix sources beyond displaying a black field.

The chassis/thunderbolt connection has been proven to work on this same computer with a Blackmagic quad card which worked fine, and those Blackmagic sources worked in Catalyst.

I realize that El Capitan is nobody's favorite version of OSX for Catalyst but in Apple's "we know best" attitude they of course make it nearly impossible to roll back to a prior OS…and I haven't been able to accomplish it despite several hours of trying.

The Active Silicon website states that their drivers are for "10.10 and later…" but it's not working on this end.

Suggestions? I'm game for tips that either get it working on this OS release or how to roll OSX back to Mavericks or Yosemite, if that's what it takes.

Thanks

Update!

I own (7) of the top-end Phoenix cards (dual/PE4) and it turns out that the first two cards that I tested with the new TrashCan didn't work…at which point I gave up and believed there was a problem with the platform or OS drivers…

Upon testing of the remaining cards, I've found that the other five work as expected! I did a ton of swapping cards around and trying to see if the problem followed certain cards or followed cards in PCIe slots. The problem always followed the two cards.

Here's where it gets really interesting. I went back and tested those two suspect cards in an old [silver] Mac Pro and they work fine there. So weird.

I'll contact Active Silicon to see if they know of problems with certain runs/builds/series' of the cards. Maybe they can flash the cards' firmware or something.

Anybody else had this problem?

Not direct related, but might worth trying.

Do you have an image of 10.10 on an external HD or know someone who has it. You might then start your new mac pro from that HD and clone the 10.10 over to the trashcan...
Thats the way I do it when my machines come back from rental. Might worth try