I had 100% mana before i did Smite, i was wearing an iron armor (not enchanted) and i have smite bound to a diamond hoe. i had no potions in a long time, and no "buffs" were on me at the time.... I believe i got all the factors... i always have /hero verbose on so that was the first time i noticed it, but at the same time, i hadnt been online for a few days so maybe there was an update that messed that up.... hold on, i will test it out again, and post again, if the glitch is still there