Verify nLight devices are being discovered:
Are the nLight devices in rapid-flash-double blink discovery mode? If they are then it may be a faulty wire or possibly the connector/communication chip itself damaged on nLight port of Fresco. Connect a known good nLight device with known good cable. Possibly test with another Fresco unit.
Check for no other bridge/other polling capable nLight devices:
Make sure there is no nCommKit, Bridge, Gateway, connected on the nLight bus.
Verify nPoller version:
On the Menu -> About screen it states the nLight Firmware Version. This is the version information for the internal nPoller device Fresco uses to communicate with rest of nLight network. It may need to be updated. Last few characters will be a Z-??? number.
Verify nPoller is discovering:
Verify the nPoller (Fresco internal nLight device) is trying to discover. You can do this be peering through the connector ports such as the 4-pin connector on the back of Frseco. With no other nLight devices connected, you can see a small rapid-flash double-blinking LED. This is only visible through a couple of the ports on back of Fresco and it will only be blinking like this when it is trying to discover nLight devices (so unplug any existing nLight devices and wait a few seconds).
Power cycle Fresco:
If none of the previous steps fixed the problem, power cycle Fresco by selecting Restart in the About tab. After Fresco restarts return to the nLight tab and wait for discovering to be complete. If devices are still missing, force a redraw by going to another tab and returning to the nLight tab after waiting for a short period of time (about 30 seconds).