2.8 grease pencil newbie question


I open a new 2D animation job. I start drawing circles on the “stroke” object. After a few circles the lines disappear. I can see what I’ve drawn, if I switch to edit mode, but in the drawing mode there is nothing. And I can’t get the lines visible in the drawing mode. Now if I then add a blank grease pencil object, I can draw as many circles as I want, and they all stay visible no matter how many lines I draw. I do not understand the logic here. What am I missing? I looked at the grease pencil fundamentals videos, but the tutor is drawing his sketch just fine on “stroke” object.

What makes me even more confused is, that as I was just testing this, on one occasion it worked just fine. The lines did not disappear in the drawing mode. And I don’t understand why.

The question is twofold: Can I get the lines back in sight in the drawing mode somehow? What exactly is it that I am doing wrong or not understanding? Is there a secret button I need to push, do I have too ancient equipment (an old Mac (2011) with OS X 10.11.6), or is it just magic?

I have a few more questions like this regarding the animation, but one step at a time…

Thanks in advance!