When you transfer from Ticketmaster, the email you put in the transfer will get the email from Ticketmaster; however, if someone else is logged into the computer or app when the link is opened will actually be the ones accepting the transfer. Also, it could be that the email address on file with Ticketmaster is under a different person's name. As long as you transferred the tickets to the email address on the order and confirmed on StubHub that you transferred the tickets, you will be fine. Also, keep the email receipts showing you transferred and the tickets were accepted. You'll never speak to anyone at Ticketmaster as they do everything via chat and email. StubHub has long wait times so unless you are really patient, you won't talk to anyone there either.
Also remember to confirm the trasnfer in your Stubhub account