Progress bar doesn’t cover full width

Hi there!
After installing the Astra Pro theme I discovered this nice plugin.
After installing and setting I see that the progress bar covers only approx. 80% of the width of the screen, so that it looks like there’s more content, but there’s nothing more to scroll…
I tried some settings changes, and tested short and long topics (it’s needed on a Learndash topic) but it makes no difference.
Is there something to do about this or is there a dev willing to take a look?

Thanks in advance!