2.8 How can I draw and fill a closed shape in 2D? I was drawing something in 2d today when 2 hours of work went up in flames as I couldn't fill in any colors.

Was this a bug/glitch within the 2.80 Beta, or am I missing something?

I would use the fill to fill in a space, fully enclosed, but it would just make a rectangle, and not work. Is there something I am missing?
Blender 2.8: Grease Pencil Fill Brush Not Working

Set the fill in the Properties panel > Material section (same place as you would set the material for a mesh).  It's a little Check box.