We have a weird issue with the 404 Pages within Fuel / CI. It seems that it is possible to hit a 404 error in different ways. The issue we have is that we are able to hit a 404 page on which CI has not been initialised. This occurs if we attempt to hit a URL that has a controller but no method. For example:
This will cause the CodeIgniters 404 to fire which does not have an instance of CI as such we are unable to use things such as fuel_nav.
If you were to navigate to url.com/unkownpage then this will trigger the fuel 404 override. I have been able to replicate this issue in a fresh build of fuel using the latest develop build. I've pushed a copy of my test project to git: https://github.com/wardy484/fuelcms404