An old iOS mobile data bug seems to have resurfaced in iOS 12.3 and seemingly iOS 12.4. The cellular data switch in iOS 12.3 is broken and allowing apps to use mobile data despite them being unchecked from accessing cellular data.

For example, if you have set up apps like YouTube and Overcast to not have access to mobile data from Settings -> Cellular, they will still end using mobile data and run through your monthly data limit.

The issue has been reported by mjtsai and confirmed to be present by Overcast founder Marco Arment who has received numerous complaints from Overcast users about this. While the original post claims the issue is present in iOS 12.3.1, it is seemingly also there in iOS 12.4.

https://twitter.com/marcoarment/status/1154923637012606979

For now, the only solution to fix the broken cellular data switch in iOS 12.3 – iOS 12.4 is to turn the feature back on, restart one’s iPhone/iPad, and then toggle it off again.

For people with access to high-speed LTE mobile data with a massive monthly data cap, this bug might not be a major issue. However, for iPhone users who live in not so developed parts of the world where mobile data is still expensive, this bug is a major issue. With the bug now being picked up by the media, I would expect Apple to roll out a fix for it soon provided it has not already fixed the issue in iOS 12.4.

Did you experience the broken cellular data switch on your iPhone or iPad after blowing through your monthly mobile data limit? Drop a comment and share your experience with us.