it must be just a bug, if it goes "on" after pressing it it still looks "on" but it actually just got on when you pressed, the settings for data use when limited wifi have nothing to do with it, if you have data disabled, all those options are off, it wont enable data because of that, all it does is switch to cell data when it detects there is no internet coming from wifi, kind of like a backup connection, so it stays connected to wifi until it starts receiving internet from it and then it stops using cell data again, but it wont do that if you don't have data enabled in the first place, annoying but nothing to worry about, if you see that bug just go manually to settings-cellular and you should see data is still disabled