[whpalmer4]

What do you mean by toggling back and forth between the different diagram styles?

I was unable to reproduce this behavior from your description, probably meaning we are doing different things, not suggesting that you aren't experiencing a problem. Perhaps posting a screen capture would help.

If you do have unwanted points on a line, tap and hold on them to bring up the Delete popup to remove them. I suspect you are accidentally adding midpoints by double tapping the lines in drawing mode.