In your model, there are two parts, (1) beam with slab (2) only beam.
Now, in the second model the beam end force matches with that of the support reaction.
But is the first model, the member end force is not same as the corresponding vertical reaction.
The reason being is, in this model the support node is being shared by both the beam and plate element. Now the vertical reaction at the support is being transmitted by the beam end shear and also the plate out of plane shear stress. The plate thickness is significantly higher that that of the connected beam underneath, that means the plate is contribution larger share of the force which is why the beam end force (Fy ) is around 15 KN and the support reaction is 1000 KN.
Now, in the second model the beam end force matches with that of the support reaction.
But is the first model, the member end force is not same as the corresponding vertical reaction.
The reason being is, in this model the support node is being shared by both the beam and plate element. Now the vertical reaction at the support is being transmitted by the beam end shear and also the plate out of plane shear stress. The plate thickness is significantly higher that that of the connected beam underneath, that means the plate is contribution larger share of the force which is why the beam end force (Fy ) is around 15 KN and the support reaction is 1000 KN.