SOLVED: The strangest thing, I'm using 2 sims and I was in middle of work when this blasted issue came up. So I swapped SIMS so I could continue making calls and lo and behold! I noticed VOLTE was working on both SIM trays!
So I swapped the SIMS again and now everything is working perfectly.
@twothrones7A hope you manage to resolve your issue. I was just about to very badly regret going for an ASUS and I actually love this phone! It's features like great battery and speakers actually make it a great work phone, I'm probably the only one who bought this for work. And it beats paying the silly asking amounts for flagship phones today!