For other people in this situation, here is what worked for me.
As I said, this is the same problem that has been plaguing Samsung trade-ins for years but some representatives seem more willing to investigate the case right away rather than wait 3-5 days.
So my thoughts on the S10 Trade in. i sent in my Note 8 as part of the trade in. It was declined as me not sending in the correct device.
I contacted Samsung to get clarification which they could not provide. I requested my device to be sent back to me. I received the package and was returned an S7 edge with a cracked screen. I am fighting with them still as it has been 11 days since receiving that. Mind you that an S7 was not even part of the deal. Deal was for an S9 S9+ and note 8 and 9 to get the credit. I never even had an S7 edge in my life. it was never registered to my account but they claim they sent back what i sent them. I already complained to the BBB and am challenging the charge back to my account.
I wish all good luck on there trade-in.
I just had my trade-in invalidated because I didn't reset the phone, but that is completely false. When I sent it in, it was at the setup screen. I will not be buying any more samsung devices. This is such a crooked bait and switch program. I hope they are hit with a class action lawsuit.