Having trouble transferring Amex Rewards points to my British Avios account. Note that I've never actually previously flown BA or accrued/transferred points in Avios, so my current points balance is zero.

I linked my BA Avios account and initiated a transfer. The points were deducted from my Amex account with the status "Points Transferred: Partner Transfer." However, within a few minutes, those points were credited back into my account with "Points Credited: Cancelled Partner Transfer."

I attempted to do another transfer, but this time, it said "could not process your request - please call Amex."

I called Amex Rewards, and they said everything on Amex's end worked properly, but BA Avios rejected the transfer for some reason. They said there's nothing further Amex can do, and it's up to me to call BA Avios, figure out why the request was rejected, and have them "clear out" whatever block is in the system. Amex apparently won't even try to do another transfer to BA unless/until BA clears it up.

Is this a HUACA situation? Do I try delinking my BA Avios account and relinking it online to "clear" the system on my own, or is this a legitimate problem I need to clear up with BA on their end?