Sorcery Passive won't Proc

Might be me misunderstanding, but in my last test my Mage has both Fire and Sorcey passive skills.

While Fire stacks has the normal proc lvl indicated in the top right corner of the screen, next to the mini map, (and the rate is 35% of skill hits)

I can't see the Sorcery stacks using the proper skills (and there the chance is 45%).

I was trying to figure out if: 

1.  it was intended like this, so I can't have a visual effect of the stacks (while the other Elements do)
2.  it is only a missing visual count (the icon won't appear) but the stacks apply in the "background"
3.  it doesn't proc at all as the skill is bugged for real
4.  I completely misunderstood the description and it's my fault

Thank you in advance for the answer

Sorcery Mastery applies a debuff called Mystic Weakening on to your target, so only your target will see stacks build up.