Sometimes an update fails, internet connections get disrupted or hardware goes bad. To fix a VMcast stream showing a black screen in the Broadcast Area, a hard reset of the Amazon FireTV Stick may help.
Unplug the Amazon FireTV Stick from its power source. Wait at least a minute and reconnect it to the power. Relaunch the VMcast app and play your loop. If you still experience the same issue, please see our troubleshooting steps or contact us.