My carrier settings got updated too, I have iOS 12.3.1 running on iPhone X
I am not facing any call / sms failure with wifi calling enabled, infact this setting has always been active on my device.
I also have jiofiber at home, I'll see if shows Jiowifi symbol tonight when I go home.
But isn't this setting supposed to kick off only when there is poor cellular reception ? I have jio tower next to my building and full signal strength, so not sure if jio wifi will work.
It still does not show any Jio Wifi symbol, even when I am connected to Gigafiber.