I looked at your project...you are simulating a Microstrip rather than two coupled microstrips in the model with no symmetry boundary. If you resolve this by making non model (or deleting) the boxes that are shorting your coupled micrtostrips your even and odd modes should be fine.
Also, in your symmetry models there are points to note...when dealing with simulations with multiple modes, rarely does the modes share symmetry as in this case. It makes more sense just to simulate the whole crossection and observe the modes of interest without symmetry. Even when using symmetry, if you are not using the symmetry boundaries, which you are not, you need to set the impedance multiplier to accomodate for the fact that symmetry is being used. Set this by going to HFSS -> Excitations -> Edit Impedance Multiplier. If you are using symmetry boundaries, it will prompt you for both the kind of symmetry and the impedance multiplier. For E symmetry, multiplier is 2...For H symmetry, multiplier is 0.5. If you are curious about the multipliers, there is a short derivation in the help.