You are right 90% if I understand your explanation correctly.

As I have explained before. Phased (23031b) should flip after the defense in concluded.

1. Enemy attacks.

2. Hero is declared as defender.

3. Hero Interrupt is prompt to used. (Eg. Never Back Down 14014)

4. Use Hero Interrupt to get +DEF and create Delay Effect (Stunned from 14014). Then, the event card is discarded.

5. Flip enemy boost, calculate ATK. Then, minus ATK with total DEF.

6. Deal that many ATK as damage to the defending Hero which all would be prevented since Phased is still in play and Hero is defending.

7. Resolve Delay Effect (from point 4) as it is a Hero Interrupt and Retaliate also resolves.

8. Phased (23031b) is a Forced Response, so it resolves now (and it flips only in this step).

9. Any other Hero Response(s) resolves as player choose order. 

If your fix version is kind of or behave like these steps, then I believe you have fixed it.

--------------------------------------------------------------------------------------------------------

I have found another tricky bug from Powerful Punch (32014)

Powerful Punch (32014) it read:

Hero Interrupt (attack/defense): When an enemy initiates an attack, deal 4 damage to that enemy.

it doesn't flip Solid (23031a) as it should as the video have shown. Here is the Q/A from people who sent Email asking about this interaction.

174 – Let’s say I am playing Shadowcat and I am in Solid form. I play Powerful Punch to interrupt the villain’s attack against me. 
At which points in the enemy attack steps do I resolve interactions for Powerful Punch (after playing it) since it’s both an attack and a defense?
Below is how I believe I would resolve relevant triggers.
1) Powerful Punch’s damage resolves. 2) “After attacks” condition becomes true. 3)I choose to trigger her Solid form in response to attacking with Powerful Punch. 4) Shadowcat is now in Phased form. 5) Having played Powerful Punch, Shadowcat is defending the attack.
Is this correct?
And, since Shadowcat is now defending an attack, the villain’s attack proceeds. Let’s say, as an example, it proceeds like this:
Step 1: boost card
Step 2: a defender is chosen or not. (Shadowcat is already considered to be defending through Powerful Punch being a defense event, I choose not to exhaust to apply my DEF. )
Step 3: flip boost card- Check boost ability- Increase villain’s ATK by the amount of boost icons- Discard the boost card
Step 4: deal damage. (Shadowcat takes no damage because she is defending in Phased form, having played Powerful Punch.)
Step 5: the villain’s attack completes.
After the attack completes, the ‘After you defend’ check occurs and I am forced to trigger Phased’s response and return to Solid Mass form.
I can trigger Indomitable (if a boost ability or treachery exhausted me), Electrostatic armor, and Unflappable. 
Is this correct?

What you’re saying seems to be correct. Let me affirm the steps:

• Shadowcat starts in Solid form.
• Villain is about to attack.
• Shadowcat plays Powerful Punch as an interrupt to the activation. She has made an attack, dealing 4 damage. She is able to flip her mass form at this point (Solid > Phased).
• With Powerful Punch, Shadowcat has made herself the defender of the attack.
• Villain’s attack continues, receiving boost card(s), flipping the boost card(s), dealing damage accordingly.
• Shadowcat, currently in Phased form, does not take any damage since she’s defending.
• The villain’s attack ends.
• Shadowcat must flip from Phased to Solid due to Phased’s Forced Response.
• Since Shadowcat defended, she can trigger Indomitable, Electrostatic Armor, and/or Unflappable at this point.

-Alex – October 14, 2022

Latest FFG Rulings (pre-RRG 1.5) – Hall of Heroes