Ward gained from Mind's Shield in the Focus skill tree is less than expected

[Tesarul]

I had put 5 points into “Mind’s shield” in the Focus skill tree and was disappointed with the results, so I did some testing.
When I start using Focus at -15 mana and finish at 344 mana I only get a burst of 103 ward instead of the ~180 I should normally gain.
I have also picked Null Infusion / Null Profusion (+ Calm Mind) and I feel like the mana burst from these nodes might not be accounted for in the calculation (unless that’s intended?).

[HybridLyte]

The mana gained from Calm Mind is only applied to the mana gained while you are currently negative in mana. This may be why the ward you gain is less than it might seem.