Coincidentally 4 of my 6 miners just got the 'blank mining data' issue. Tried hard reboots to no avail. Tried to power them up first and then fire up the pi after, still no luck. Switched form antpool to F2pool and they all came back up 100%. Weird they wont show the connected devices, wattage, etc until they connect to a pool. Thinking the pool is related in some way as I have only been mining on Antpool when this has happened. IDK... Best of luck on experiment tonight rootdude.