CI4 Routing Issue (Resolved)

I have tried everything I can think of with this problem. I have got the URI helper to output the current URI which correctly shows no index.php in the URI, so from that I presume the .htaccess is working right.

Every time domain.com/segment1 always follows the specific routing, but when you have domain.com/segment1/segment2, it just does not follow the routing procedures. I have also tried with segment1 as a group. With the 'get' route of / within that group, it again routes fine. But put segment2 within that group, and the routing is never followed.

Could the core framework need reinstalling?
Rich