Pattern Brush start and end components should not appear when used on closed paths as in Illustrator CS6.
if you make a pattern brush with a red dot at the end, you can use it to find open paths in CS6 but not in CC2018. necessary for working with plotter/cutters.
I believe it’s fixed. If you still have a case when this doesn’t work for you, please comment back and share a test file directly in the comments (if you are allowed to), or send it over to firstname.lastname@example.org, providing the link to this report (https://illustrator.uservoice.com/forums/601447/suggestions/35328586)
It should be a brush option though, because changing it will ruin existing artworks.
Please add this option and make it not default.