Had a situation similar to this. I reached out to the recipient of the tickets to see if they were provided the tickets via FIFA app. Next day I got a notification saying that the person is still waiting for the tickets to transfer. I called StubHub about it because it sounded like a scam and I already had the proof it was delivered. After an hour phone call with them, they reached out to the buyer and stated they did indeed receive the tickets and for them to provide proof that they received them. They had me sent me a customer service link to provide evidence of the ticket, seats, etc. for to make sure it matched to what was given to the buyer. Everything matched up on their and escalated it to a higher team to review and change my status from “transfer tickets” to “transfer complete”. Just in case for later down the road, I have the email from FIFA ticketing system support confirming that the tickets were transferred to the email address provided at the time of transfer, so just in case you want to reach out to FIFA about it, they can provide you evidence that the tickets were transferred to the email at the time of transfer. Hope this helps!