Hello @Stella28,
During the propagation, the spacecraft has an attitude profile attached to it defined by an AttitudeProvider, which you can optionally pass during construction of the NumericalPropagator. If you don’t specify it, the propagator uses a default attitude model. I don’t exactly remember what’s the default attitude, but I seem to remember that for quasi-circular orbits the X axis is aligned with velocity and Z with opposite of position vector (take the “aligned” with a grain of salt, since I don’t know if the attitude is position-based or velocity-based).
When you build a maneuver you can specify a new attitude that overrides the one used during propagation. This attitude is only used to compute the thrust vector and does not affect other forces that depend on the attitude of the satellite (like drag if you are using a non-isotropic body shape), as was asked (by me a while ago 
) here.
In your case, the propagator is using the default attitude to compute the maneuver direction. In general, I’d say it’s better to specify the attitude override when building the maneuver to be sure that the thrust direction is the one you really want when transformed in the inertial frame for the integration.