Thanks for getting in touch, it was Windows 10 using Chrome. I've now uninstalled the app, moved to Edge and created a Windows app in it. That's working fine although it did make me register a device switch, which at least I was able to do, the functionality had disappeared in the previous version.
With the Android app it's running fine now, it's on an old Telly Tablet which doesn't seem to want to update anymore so I imagine this will cause issues again in the future.
If you have any further issues with TV Go from here or need anything else, please don't hesitate to get back in touch.