Thanks all. I'm going to revisit that bridge (and outro section using the same progression). It does need a lift to get some more dynamic in there. Also, the relative balance needs modifying in those sections, which may be part of the reason.
Finally, since I moved house, I haven't even set any speakers up in my room. Plus I have a new pair of headphones to replace my old Sennheisers which fell apart after 10 years. All of which means I'm mixing on a pair of headphones which I don't know well at all!
Wood
Studio One 3 Pro, (Sonar Platinum), Intel i7, Win10 Pro, 32Gb ram, RME Babyface Pro, Behringer X-Touch, Presonus Faderport, Akai MPK49, Arturia KeyLab25, KRK Rokit 5 monitors, and other sonic surprises.