Hey. No i couldn't tell you what my income was but it was lower for alloy. (Had the same lvl of buildings on everything but less skillpoints in alloy income). And as said before it sometimes works most of the time it doesn't.. At the moment it works, i get less alloy then the others.
Hope that works and sorry it got a little late.
IM not sure but last time it happened around when i used resource knowledge in operations. Then it works again after quite a while. Maybe when its off cooldown or something... Have no idea if thats what makes it happen, just a thought