Apparently, it was nothing to do with the Jio CC. It was my router DNS, that was causing the VoWiFi to not work. I use AdGuard DNS on my router and Jio VoWiFi isn't working on it. As soon as I switched to Google DNS, it started showing up. I changed the DNS on my phone for some other reason and this shown up and I thought Jio CC did something. However, when I switched back to AdGuard DNS, this was gone again making me realize it is the DNS that's causing it. So, if any of you are using custom DNS (Like AdGuard) and not getting VoWiFi on Jio, try Google DNS.