For some events, there are delivery delays in place that restrict the release of the mobile QR codes until closer to the event start (sometimes as close as 24 hours).
Once you have accepted your transfer, the ticket(s) will be visible in the my events tab on the platform you accepted the tickets from (ex. Ticketmaster, AXS, Seatgeek, etc.) The barcodes will become available as soon as the delivery delay is released by the venue or team.