Burden of the Father boss can be knocked back into the wall

Since this is a bug that happens to everyone in every party of every class in every world on every system, some of the answers are obviously, "every".

Time: Any
Frequency: Every time any knockback effects are used on the legs or body
World name: Every (mine is Jenova)
Character name: Everyone
NPC name: N/A
Monster name: The Manipulator
Class/Level: Every class with a pushback attack like SCH, WHM, MCH..
Party or solo: Party
In-game time: Any
Area and coordinates: The Burden of the Father
Steps:
1. Hit the boss with a pushback attack.
2. Watch him get pushed back, but the leg hitboxes remain in the same place.
3. Cry, as you realize that the tank has to stack with everyone becayse Manipulator's body is now unreachable.
4. Wipe.

Note: This only happens since 3.1 released. Pre-patch, the boss and legs wer not pushable, so of course many people are unknowingly causing the fight to be unbeatable.

Connection Specs
- Type of internet connection/provider: Every
- Modem maker/model number: Every

PC Specs
-=-=-=-=- System Information -=-=-=-=-

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Laptop Model Name: Every
Laptop Model Number: Every

Gamepad Manufacturer: Every
Gamepad Model Name: Every
Gamepad Part Number: Every

Browser Information
- Name and version of the browser currently in-use: Chrome
- Internet Explorer Version: whatever comes with Windows 10