Is Transformer shield bugged?

While Amara’s Spiritual Driver is active (i.e. an action skill element is applied to self), self inflicted shock damage doesn’t seem to regenerate shields. Only when the action skill is not active does it work. Is this by design or a bug?

I don’t use that MOD but I have noticed odd behavior with this shield at times and so have others. I have a thread I created about it recently:

Not sure if what you are noticing is related to what some of us are seeing at times or it’s different things but worth consideration.

It seems to work very reliably for me, unless I’m taking another type of dot damage, then it doesn’t work at all (at least for shock damage I apply to myself). FWIW I’m using a shock fastball to proc transformer.