Dear Greg, sorry for missing this before.
We have tried the steps you mentioned above and we found that it is not a bug.
Please note that the five line width options are set by default from 2 pixels to 10 pixels. (2/4/6/8/10)
However, you could change the line width as you like below in the cursor. Please note that this won’t change the five line width options.
1 - choose the width line tool (there are five “L” with a dot below the selected one)
2 - choose the thinnest width (the 1st “L”) and move the cursor to the left to set 1 pixel width for example
3 - draw a line and come back to the width line tool. (here you will notice that there is no dot under the “L” anymore) (Because you change the line width as you like, instead of choosing one of the line width option)
4 - choose an other width line (the 2nd “L” for example) and draw something.
5 - finally when you come back the thinnest width selection (the 1st “L”), you will notice that it is set back to 2 pixels and not 1 pixel as you have chosen before at the 2nd step.
(Because the 1st “L” is set by default at 2 pixels, we could not change it.)