Broken pencil line

Hello. Please, help

  1. I made a figure A by one whole line using pensil.
  2. Then I add new figure B, which connected to figure A and fill figure B by paint tool.

As a result my figure A line became broken. Look at the picture. I want the figure A line to be unbroken.

Which setting should I change to revise this situation?

Thank you

Try unchecking the “flatten” option for the tool you are using in
the “Tool Properties” window.