This happens with me - I've got MSI R9 290's and running litecoin bamt 1.2.
It's almost as if occasionally the api get's blocked or something. Either one or both of the cards disappears from gpumon and the web gui
Very strange - wish I knew how to fix it
It's happening to me to, with BAMT 1.2/NotSMOS. I'm using two Gigabyte R9 290's.
Sometimes the web interface will drop to 0 and show neither card, and sometimes the browser will just refresh to programming jibberish with the error:
"Can't use an undefined value as a Hash" and then it complains about not being able to write to a death log file because of file permissions. ANd 10 seconds later it will autorefresh and show one or both cards running.
LXTerminal is also flakey for me, usually it's the second card (GPU 1) whose entire column disappears, and then when it does reappear it's full of hash rates, like it was being recorded the entire time.