I find similar problems when connecting a WatchPax 60 to 3 Novastar LED-controllers. For the first trials everything went well but after updating the WP60 software it looks like EDID is messed up. Changing the GPU settings didn't help much and as you say the display settings pops up on one of the outputs while the others are blank.
Checked the WP60 outputs on a standard HDMI-monitor which is looking fine. Connecting other sources to the Novastars also works as expected. But no luck connecting WP60->Novastar.