AutoDesk Smoke :: 16bits FP Not Supported

following the Action Workflow pt 1 tutorial with my own footage.

1] I have a background track and green screen track above it. I apply timeline axis effect Master Keyer and create an awesome key.

2] I select both layers and create CFX. My awesome Master Keyer key is now changed back to a a luma key or something.

3] I go into Action, select media and click on the K in the media list. In the lower left of the screen the following message flashes quickly (I have to click many times to read it. It doesn't stay on long)

"16bits FP not supported"

4] I note that both my background layer and my foreground layer say the following [12->16f) I think that means 12 bit is being converted to 16bit. Not sure why. I never asked it to do that. So I click on the clip in the CFX schematic. I see RGB LUT is Active I change both to 10 bit. Same result. I try 12 bit. Same. If I change these setting in RGB LUT I am not permitted to leave the CFX editor, so I change back. I make sure resize is on.

Anyway, the tutorial is cool because the keyed footage just shows up right immediately upon entering CFX. I'm not so lucky.

How do I get green screen footage into Action? Bottom Layer is 1080, top greenscreen is RED 4k. Resize is on for RED footage. Changing bit depth makes things weird and doesn't provide a result.

If I hit reset in the Action node Media panel the K disappears. I can now double click on the empty space and up pops that godsend Modular keyer.