Yep, the FTB launcher doesn't have any hooks for Evolve to use. In theory, it might still have worked if there was only one modpack. With there being multiple to choose from, Evolve can't really interpret what you want it to do. You possibly can direct it to the saved modpack once you downloaded it and create a startup script (please google how, as this depends on your OS).
Or, in all fairness, just use the standard FTB one. Evolve is nice and all, but the quality/CPU-usage ratio for recording is mediocre at most. For recording tools, I suggest you either use
OBS or, if you have the required hardware,
Shadowplay.