You can call meeting services (same number you would have used to confirm it unless you did it online when that functionality worked). The problem you may face, like others have (including me) is that you get the email confirming the upgrade from BusinessExtra showing the seat. But did you get an email showing the ticket was actually reissued? If not, you may find that you can't check in and you wind up in a middle seat by the lav. If you have the experience I did, the rep put me on hold when I inquired about my BXP3 cert being redeposited on 12/16 for a March 2024 flight that was confirmed by BE. She came back and told me they moved the seat back to coach because "the upgrade was never paid for" (despite me having a confirmation email). It went nowhere, but suffice to to say it sounds like the lack of any ticket re-issue is what caused my upgrade to get kicked out.
I called meeting services. They said everything looks good on their end. They said the best thing for me to do is to try to check in at 24 hours if it doesn’t allow me to check in then to give them a call back while they’re open that morning, that works for me and at least it’s a record that I tried here.