Bug (?) with StreamTracer pointcloud

I have a vector field, and when I create a StreamTracer cloud point filter, I face an annoying bug. I take time to specify the center of the ball that seeds the streamlines, I take time to pick a number of seed points and it works “fine”, I have a finished picture:

However when I click back elsewhere, for example on the vector field’s data, many streamlines are suddenly removed!

I can go back to the StreamTracer picture again, but if I disable the Show Sphere option (because I indeed do not want to see it), then many stream lines disappear, exactly as if I had clicked on some other field!

Here is the annoying end result…:

I really wonder how do people deal with this? How do you guys prepare your stream lines?