Do you have "passphrases" enabled on your Trezor device? If so, is there a possibility that when you first setup the MultiSig you unlocked the device using a non-blank passphrase? 
No, I did not set a passphrase... but at this point, yea, I have contacted Trezor support and hopefully they can manage to find a solution.
Thank you for the help, I'll keep this updated for future reference.