I hope that you've been able to activate your phone by now. I had a similar issue, and after a month of trying, I was finally able to get my new iphone 11 activated. I had had service with Visible for 2 yrs 3 months on my Google Pixel 4A when I change/upgrade to an iPhone 11.
As of last night, 1.7.2023, after a month of attempting to get my iphone 11 activated on Visible, I did one last ditch attempt. I first logged in to Visible and requested to port my number, which is what you have to do to move it. I was angry enough to move my service so that I could have a functioning phone if one more chat (after many hours & many chats) didn't get me someone who could fix my phone so I could use it!