You can get singular.live and CasparCG to work together beautifully with the following workaround.
Download the free singular.live recast for NDI application (windows) from Singular.live Recast for NDI
You can install and run this on the CasparCG server computer. Enter the singular.live output url in Recast and click start.
Verify the NDI url with the free NDI Tools Studio Monitor software.
Then give the following CasparCG ACMP command:
PLAY 1-10 “ndi://server/stream”
Example:
PLAY 1-10 “ndi://CASPARCG01/cef-ndi”
This works beautifully. With fill and key if the outputs are configured correctly in caspar.