I haven't seen any other people with this problem, so I'll ask here. I have a 3-tier supply unit in my map, each one producing more supply than the previous. However, as soon as you start the upgrade for the next tier you get the supply instead of when the upgrade is complete. I have delayed the 'abilities', 'actor', and 'stats' under the upgrade ability info, but they don't seem to affect the supply limit. What am I missing?
Supply probably is considered a "cost" type value rather than a unit stat, upgrading to a higher supply cost is processed when you try to give the order after all. If you've tried all morph and cost settings, just give the additional supplies via a hidden buff (see Terran Supply Drop) and apply that as a morph end effect.