Hi there miners!
I have the same problem. When I found my miner was offline for a couple of hours I tried powering off and powering on. At first I did get show many xxxx xxxx and after 2-3 reboots the chain was gone completely. Thanks for pointing out that the hashrate is still 19 GH/s. I switched pools for testing and the pool also reports 19 GH/s so I suppose there is some sensor missing showing the chain or firmware is buggy.
Nevertheless I realized the temperature was too cold because I left the windows open. Now I put the miners some place warmer and even only with 40% fan speed they are working smooth now (still with one chain missing).
Just wanted to share my experience. Don't panic... check if you can change the environment, test some different placement or even pool.
Kind Regards!
I am facing the same issue. My D3 antminer is missing one chain. Its not showing up Please let me know if some one has solution My miner status saying
~18000 Mh/s still and sometimes it reaches to over 19000 mh/s. How it could be possible if one chain is missing. Either its working but now showing up on miner status.
Same problem.
I cant see chain no 3, working 19,5GH/s, its interesting. ( I think its nicehash hack effect

)
Chain# ASIC# Frequency GH/S(RT) HW Temp(PCB) Temp(Chip) ASIC status
1 60 537 6409.59 2 54 76 oooooooo oooooooo oooooooo oooooooo oooooooo oooooooo oooooooo oooo
2 60 537 6455.22 0 52 74 oooooooo oooooooo oooooooo oooooooo oooooooo oooooooo oooooooo oooo