I had a troop in play, prophesied by Cyclone Shaman, but no actions in my crypt that the ability could target. Then I cast Heroic Echo with the chest equipment to make a copy of that troop, a copy was created with the prophecy ability but it did not trigger to get back the Heroic Echo (in all cases the troop had cost greater than the Heroic Echo). The ability triggers, and can get back the Echo I just cast as long as there's already a target for the Cyclone Shaman ability in the crypt.

This bug also happens with Archmage Wrenlocke's glove equipment. Casting Heroic Echo on Wrenlocke with no actions in the crypt and the glove ability doesn't trigger. Casting Heroic Echo with at least one other action in the crypt lets you get back the Heroic Echo.