Trap/blasphemy interaction inconsistency

There is an inconsistency with the interaction of the blasphemy support gem when also linked to a trap support.

Follow these steps: (I used vulnerability curse for this, haven't tested with other curses)

1. Get an item with at least 3 linked sockets, 2 blue and 1 green.
2. Socket Vulnerability and Blasphemy support. Do NOT socket Trap support.
3. Activate the blasphemy aura.
4. Socket the Trap support gem in with the blasphemy set up.
5. The blasphemy aura stays active on the character, however the skill in the skill bar now functions as a trap as expected, but no mana is consumed when throwing the trap, despite the tooltip showing a 42% mana cost.

If the Trap support gem is socketed in while the blasphemy aura is not active, then the skill will properly consume mana and the player character will not have the curse aura. As far as I know, this is the expected behavior, as opposed to what is described in step 5 above.