By the time you dragged the view, the sketch was probably hidden in the assembly. Go and look for the sketch in the tree on the left and right click and show.
For me, your sketch was hidden in your AS when you created your MEP, if your sketch is apparent in your AS and in your MEP the sketches are apparent, then when you drag your view, the sketches are apparent. On the other hand, if it wasn't the case on the 1st view, even if you change the display in the As or the MEP, it's too late and SW continues to hide the sketches. The attached proof:
To check my say, redo a new MEP shows the sketches in display. Drag a view of an AS with an apparent sketch.
Thank you @sbadenis I tested with another type of drawing and I actually don't have the problem. The Sketches remain visible. Which means that there must be a checkbox option in the settings of my other document template. Do you have any idea what it can be?
As said if you start dragging the view with visible sketch no worries on the other hand if you start with a sketch not visible in display and then you change SW keeps the behavior of hiding them (bug?). So once you have created your MEp, the only solution is to redo a MEP and show the sketches before dragging.
Great, it works well. Thank you very much @sbadenis & @Cyril.f I think the problem comes from the fact that these are old drawings and that the assemblies at the time (2003...) must not have had the sketches yet. For the new drawings, no worries. For the Ancients, the visible sketches must be put back in the tree.