Exiled a Blood on the Snow from my hand - March of Wretched Sorrow (also in hand) triggered.
Next turn Exiled a Dying to Serve from my hand - March of Wretched Sorrow did not trigger.
Perhaps because it only had 2 mana left to fill on that second turn?
Thank you for all the information provided, this issue will be investigated!
If you have any additional information that you consider relevant, please don't hesitate to send me 😊