Can't Check 'USB Tethering Box'

[Back2Front]

Hi, I rely on USB tethering to communicate with the world on my computer-
But on my S4 GT-19505 running Lollypop I can no longer check the box
Settings > More Networks > Tethering and Mobile Hotspots >Usb Tethering
Its not greyed out, and plugged in with various cables says 'USB Connected - Tick to tether'

Tapping the box it visually responds as though its been tapped, but doesn't change the state to checked.

Any advise to get me back online would be super! - right now I'm spending a bunch of money to access internet via cafes.

 

[Back2Front]

So after a bunch of troubleshooting I noticed that I just had to tap the box, and wait for about 4 minutes before it turned on. Used to happen almost instantly. Atleast I'm back online.