Did you (manually) try --list-devices to see which devices it sees? Did you try manually, locally, from the miner, NOT through AM, and does this work?
Not sure what you are asking specifically, but yes, if i go through the miner directly, I can make it run only 3 GPUs.
Ahh I see - next time read the readme ;-)
--dev Space separated list of cuda devices
In short, not --dev=0,1,2 but --dev 0 1 2
(no "=", no comma)
No, the readme says
space separated but the config shows
comma separated.
dev=0,1,2 is what I'm using successfully
dev=0 1 2 and the miner will only run GPU0
I have read the readme

And that's why I can get the miner to work..... but no luck when going through Awesome Miner
Go to Options->Profit Profiles. In the Profit switching profiles select the profile that applies to you, in my case "nVidia GPU". Then select "Edit" Click on the miner you want to use. Click on it, click Configure. Then Select "new" in which at this point you can specify the number of GPU's you want to use or detect from host per device.
Following your instructions but I can't click on "new" afte Configure, the button is greyed out and unclickable. This is on DSTM Zcash Cuda Miner.