Thinking about it, that's a lot of Sublimation gear. Could it be that the effect caps? I'm not aware of any caps, but I'm not that far myself yet. At Lv99, Sublimation from SCH main will give 8MP for 2HP, and every piece (of which he mentions 3) will add 1 to both, so 5HP to 11MP. Maybe it caps at 11MP or 5HP?

Garota, you can do a proper test by checking the recovered MP amount instead of the elapsed time. Use Sublimation and use it again after it wears off and check how much MP was recovered. Best to have no Regen gear on, so you see exactly how much HP was converted to MP.