I think there is a big bug in cgminer's driver-icarus.c:

ICARUS_UNUSED_SIZE is defined as 16. IMO this should be 20.
ICARUS_WORK_DATA_OFFSET is defined as 64. IMO this should be 68.
(there are maybe even more wrong values)

Can you verify/confirm this?

So, have all the miners who use cgminer with icarus devices been misled?

BTW. the source code of this program is really a PITA to study :-(