To my understanding, in a two-body problem of a planet and a satellite, a 1:1 resonance means that the orbital period of the satellite is the same as its angular frequency (maybe not, so please correct me).
In section 2.1 of Makarov and Efroimsky, 2013 No pseudosynchronous rotation for terrestrial planets and moons they say:
For a nonzero eccentricity $e$, and in a sufficient proximity of the 1:1 resonance, the relative orientation of the perturber and the bulge changes twice over an orbital period*
I don't understand why the relative orientation of the tidal bulge changes twice, the way I see it the relative orientation should stay the same. Can someone please clarify that statement?