You initially said the 24 word seed phrase did not recover anything:
So then I entered the 24 word seed and clicked on that button. It found nothing! No accounts detected. And when I loaded the wallet there was absolutely NO TX HISTORY and the wallet was empty.
But now you are saying the 24 word seed phrase does recover their accounts:
I have entered the 24 word seed into a Trezor One I had on hand. It does recover the account showing all their tx history including where they sent the 3 Bitcoin out on December 19, 2017.
Is this the same 24 word seed phrase? Have you use any additional passphrases? Did you recover it differently on both these occasions?
At this point I am simply going to try crafting a manual bitcoin transaction using a private key derived from the 24-word seed phrase and see if when submitted the bitcoin network will move the coins for me.
It won't. Private keys are not transferable between addresses like that.
Have you had a chance to put this seed phrase in to Ian Coleman and cycle through multiple derivation paths?