I created a thread for this problem max hair&fur is missing on IR - Issues - Chaos Forum. and it was moved to resolved bug.
but the problem is still happen to me, IR randomly won’t show the hair&fur (95% appear , 5% appear). still looking for what’s really going on…
check the attachments. I uploaded the scene, you can try it.
dailybuild feb 09, max 2015 SP2.
Fixed, but I am not sure if I will be able to keep the fix. I had to re-enable something I disabled for some other reasons… so now lets wait until simebody reports a different bug caused by this fix. 3dsmax API is screwing me over hard time here.