So, when FNBO closed my lost card, they did open a new tradeline on mine. They marked the lost card tradeline as "Closed - Lost/Stolen" and opened a new tradeline. The new tradeline has the same opening date as the lost card. However, this (AFAIK) did not cause a point loss on my CRs. YMMV.
That is exactly what they did on EQ and TU. TU remains unaffected, EQ is all messed up. There's no reason for my mileage to vary with a transaction like this. EQ just has a knack for screwing up the simplest of transactions.
I would dispute it. It's not a new account, it's just a change in card number.
I wouldn't even know what to dispute. The account is reporting properly on CK for EQ. Just not sure why/how F8 reacted in such a manner. It initially showed both account numbers on all CRAs. Now, the old number is gone, but my score hasn't recovered.