iMessage contact name reverts to outdated information

Within the last week, my on my iPhone, my dad's iMessage contact information switched from Dad, which is in my contact card, to an old email address of his. I've tried to find out where this old email is stored but am unable to find where it is coming from. I've deleted the iMessage conversation, deleted his contact card, restarted my phone, had him send me a new message, saved that phone number into my contacts and added his current email address, which is also his Apple account login (old was gmail.com; new is duck.com). I replied to the new message and it changed from dad to the old gmail, attempted to send the message as SMS, and of course fails. My iPad correctly identifies the conversation with his phone number, so the issue lies in my phone. Below are screenshots of creating the new message to my dad using his phone number and my phone switching it to his old gmail account, but my iPad (second to last picture) keeps it as dad. And for anyone thinking the contact card is incorrect, that is shared too (last picture).