It can take a few days.
Not to worry you but I had another technical glitch 2 weeks ago, I contacted them, and got a canned, completely off-topic answer. It came within 48h, but was completely useless.
Looks like they hired more staff, at the expense of quality. So if you have a QR code issue, I would suggest you look into it by yourself at the same time.
Could be name/middle name related, first/last name inversion, wrong jab number selected, etc.