More stun buildup from support gem and rolling thunder not applying

Bug Report ID: #3572628290

Issue:
The 'more stun buildup' does not seem to apply from the support gem 'Overpower' support gem or from the first slam of Rolling Slam. This may be just a UI issue, but eqipping the gem and uneqipping shows no change in the Main hand stun buildup modifier stat. The First Slam details of Rolling Slam also show no increase in the same stat. It is hard to judge based on just the stun bar on enemies too but it looks like there is no difference with or without the gem being equipped on how much stun is built up, so I believe the 'More stun buildup' stat on the gem and skill is currently broke.

Steps to reproduce for skill gem:
- Open a melee attack skill's detail panel and obeserve the On hit effects - Main hand stun buildup modifier number
- Equip the 'Overpower' support gem
- Obeserve the On hit effects - Main hand stun buildup modifier number again. There is no change here when I think one should be expected.

Steps to reproduce for Rolling Slam:
- Open rolling slams skill details in the skills menu
- Open the first slam tab
- Obeserve the On hit effects - Main hand stun buildup modifier number. This will be the same as all other melee skills when it says it should have 50% more in the details of the gem when hovering the skill

The problem is always here...