Draw tool not working Correctly, it's not drawing the line

This post refers to Adobe Elements 26

When trying to use the draw tool I select the Pencil Tool, the line I wish to draw is in black and 2 pixels wide. I click on the star point and the first black dot does not appear, I then go to the finish point, holding the shift key down to get a continuous line and the line does not appear. 

This happens intermittantly, sometimes (occasionally) the line is drawn.

I have been using this feature regularly for a long time and this is the first time I have had a problem.

Similarly using the Erase tool, it acts like the brush tool

Anyone got any ideas