[Bug] Ghostly Prison not working with certain cards

[torridus]

Ghostly Prison doesn't work when Windborn Muse is on the field.

I'm using Forge 1.5.51 (released on 13 April 2016)

This bug is a little rare because it depends on AI behavior (and if they will want to try and attack you at certain points of the game). I did a quick search to see if anyone else has reported this, and came up with nothing. Might be somewhat related to this?

In the screenshot I've attached, the game was going like this:
- I have 2x Ghostly Prison and 1x Windborn Muse out, so my opponent must pay 6 mana per creature to declare an attack (2+2+2). But then:
1. AI plays Keldon Warlord, using 4 of their 6 available lands.
2. AI attacks with 3 creatures, paying 0 mana instead of 18 mana like they're supposed to.

There is no crash report or anything out of the ordinary. Forge seems to forget the Ghostly Prison effect when it applies through multiple cards.

I used Dev Mode to add 2x Ghostly Prison to a fresh battlefield. They work like they're supposed to. But then I add a Windborn Muse... and then none of these 3 cards have an effect. AI opponents can attack paying 0 mana instead of 4+. If I destroy the Muse, the Prisons work again.

I tried this with Archangel of Tithes and that works normally with Ghostly Prison. It's just Windborn Muse so far that makes Forge forget the rules.

[Hanmac]

The problem is the planeswalker:

2/1/2014: Unless some effect explicitly says otherwise, a creature that can't attack you can still attack a planeswalker you control.