Yes, I ran into that too. I found out that if you start drawing lines from one section point to another across the face you need to create that it will partially fill in. Continue to do that and you will eventually have a face with a lot of extraneous lines. Use the Eraser/control tool to soften and smooth which makes the lines go away.
Typically the cause of this is that the arcs aren’t in the same plane. Easiest approach to drawing something like this is to start with a large rectangle. Draw the outline of the part on the rectangle and erase the edges of the rectangle.
Curves, arcs, and circles are always represented by a series of straight edge segments. You can make a an arc or circle look smoother by increasing the number of sides. When you start the tool the Measurements window displays the number of sides. Type a new value if you wish.
Caution: Don’t go crazy with the number of sides. You can easily bloat your file and cause problems with geometry, especially with smaller details.
I find some multiple of 12 is best for most arcs and circles and rarely more than 96 sides are needed. With smaller details fewer sides.
A couple of examples.
Round table top with 96 sides.
Dowels and their mortises with 24 sides. The holes for the vise screw and the ones in the parallel guide are also just 24 sides.
