SGminer should define it as WORKSIZE. If even this fails, try a safe way.
Perfect. Changing to WORKSIZE did fix the problem - but the GPUs were going sick/dead very quickly. I ended up having to run with i12 -- i13 or above and the gpus get unhappy.
In addition, don't try to set thread concurrency to anything other than power of 2, i.e. 1024, 2048, 4096... It will only produce HW errors otherwise.
Oh, okay. I set tc4096 while doing the above -