Can I buy concert ticket insurance after buying tickets?

Anyone know if there are any companies that do missed event insurance that I can buy? I bought tickets for Elton John concert in 2020 and wanted ticket protection, it was showing in my basket until payment. 1 minute to go after registration, petexrion wasnt showing for some reason and I didn't want to lose tickets so husband said to purchase them and ring ticket factory after but I can't add insurance on through them. I'm waiting to hear back from securemybooking.com to find out if I can purchase it through them as they were the ones providing it on ticket factory website. Wondered if anyone knew of a company that does it incase they won't?