Mobile View Cart Stopped Working

Has anyone had recent issues with customers not being able to view the cart when accessing by phone on a mobile theme.

This seems to have just started recently yet we have not made any software changes to our site nor done any updates. It doesn't seem to matter whether it's Android or iphone.

Customer can add product to the cart, it will show 1 item in cart, but clicking the cart icon does not do anything. It works correctly however on desktop, so it's just mobile.

We are on 4.11.3 and using a responsive theme. Tried clearing caches

Any ideas would be much appreciated