Demon Form with Ghostwrithe and Ming's Heart Life Loss value

Don't know if this is the intended interaction but the combo doesn't work.

Equipping Ming's Heart in combination with Ghostwrithe doesn't affect the value that Demon Form is using to calculate the Life loss per second.

Both items work fine to calculate the value if used separately, but if combined only Ghostwrithe is used to calculate the Life loss per second value for Demon Form whilst Reduced Maximum Life from Ming's Heart is being ignored.