Possible Decaying Hex Bug

The support gem Decaying Hex, which, for those that don't know, puts a chaos dot on an enemy when you curse them with the supported curse. It works just fine when you are manually casting a curse spell, but if you put it with a curse in Blasphemy, it doesn't work. Nowhere in Decaying Hex makes you think it shouldn't work since you are cursing enemies. So I'm not sure if this is a bug or if Decaying Hex is intended to not work with Blasphemy.

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