Cellular Data per apps not working

I have an issue with my iphone 7 where the cellular data does not work, only for Phone. Whenever I'm out, i will toggle the data on for instagram or any other app and go to that app, it says im not connected so i go back to settings and it has toggled back by itself. All the articles about this are from 2015 and im the only one with this issue, restarting doesnt work, turning it on and off doesnt work, i know i have data. And the most irritating thing about all of this is that it only started happening in december. I didnt do anything different so i dont know what the issue is. There are no restrictions on this either