An AC generator can 'lock up' if its timing is off?
What you are describing sounds similar to the issue of starting a synchronous motor, where the voltage of the stator is operating at the motor/generator's nominal frequency, but the inertia of the rotor is too high to "follow" the stator frequency. The magnetic field of the stator causes a slight pull of the rotor while it cycles "away" from the rotor, but the torque induced by the stator on its half cycle toward the rotor counters the initial rotation, resulting in net-zero torque.

I have posted a figure from Stephen Chapman's book "Electric Machinery Fundamentals" which illustrates this well.
Note that induced torque is proportional to the rotor's magnetic field crossed with the stator's:
$$ \tau _{ind} \propto \boldsymbol{B_{R}}\times \boldsymbol{B_{_{S}}} $$