Temper Weapon Rage Bug

Temper weapon isn't working with rage properly.

If I have + rage on hit from the skill tree, it will only generate that rage and wont generate rage from the rage support gem.
If I have the rage support gem then it will generate rage from the support gem.
Also, I have + 2 rage on hit from the skill tree and I have a +5 rage support gem on my skill rake. When I use temper weapon I only get 2 rage, but if I don't use temper weapon I get 7 rage.

Clearly temper weapon is only applying 1 source of rage on hit at a time and if it generates rage it will prevent any other skill from getting rage. Confusing since temper weapon is a separate skill and so it should generate rage independent of the skill that triggers it.

Plz fix, this is bricking my build right now.