You probably have a few separate lines and arcs. I know you indicated you had “connect to end of selected” on but you may still have unknowingly created more than one series. Drag a box around (or select all) the lines and arcs you want to close and use “Weld” in the vertex modeling tools.
If you have drawn from the endpoints and used snapping this should work.
If “Weld” does not work, you will have to determine where the pcs do not connect and do a “Target Weld” (vertex modeling tools) on those specific points. You may have to zoom in to see the 2 points that need to be welded.