[GAMEPLAY]Strength of Ages Mastery not giving correct amount of health

The Strength of ages mastery is only giving 10 health for large monsters when it should be giving 20 like it is supposed to. I noticed this when i was playing jungle while using this mastery and at the twords the end of a game I didn't have it even close to full stacked. After i noticed this i went into a custom game to test it. I tested it 2 times And found that it only gives 10 health of health for large and epic monsters. Also the in-game tooltip shows the actual amount of health it gives you. EX: currently if you kill a large monster you gain 10 permanent health and the tooltip will also say you have gained 10 permanent health.