I wasn't able to reproduce it with the same setup they had just in SSP so it may be an SMP issue.
He said the only mod they run is BC 1.8.1.1
It was mostly reproducable for him, mostly cause it doesn't occur 100% of the time but more often than it did not happen.
Casusby, on 26 September 2011 - 04:25 AM, said:
Not sure if this has been reported? But in 1.8.1 SMP, a buildcraft server that my friends and I started up (no other mods) the furnaces eat up items when used if they have a wooden pipe connected (powered and not). Also causes any items currently held by the mouse to be dropped and the furnace animation to run even though nothing is inside the furnace now. Not really sure what's causing it as it doesn't occur everytime and we haven't found the exact cause.