1. Give us the steps to reproduce the bug

-Play and flip Invasion of Segovia
-Play a non-creature spell with casualty, and use your creatures to convoke it with
-The creatures you used to pay the convoke cost are not able to be selected to be sacrificed for the convoke (I was holding full control)

1. Note which platform you’re using (PC, Steam, Mac, Android, or iOS)

PC

1. Enter the actual results you’re experiencing

If you play a spell with casualty that has convoke from Caetus, you are not able to sacrifice creatures used to pay the convoke cost with for casualty.

1. Enter the expected results of the feature

If a card with casualty x has convoke as you cast it, you pay its total cost in any order (C.R. 601.2h). Thus, for example, you can choose to pay the mana portion of the cost (and tap some creatures rather than pay some of the mana as convoke calls for) before you sacrifice a creature with power x or greater to pay for the casualty part of the cost, if any (C.R. 702.51a, 702.153a).

Notably, compare this case with the cases described in the following, which involve mana abilities, such as [[Ashnod's Altar]]'s, in which a permanent is sacrificed (C.R. 601.2g-h):

1. Add any relevant screenshots/videos

Attached

1. If you found a workaround, please add workaround steps.

No workaround