I was just getting a feel for them working wet into dry on some practice paper (a Strathmore watercolor journal) when I got that bead. My tests were nowhere near as scientific or exacting as yours… and I rarely use a brush as large as the #8 (which is the same size as two of my other #10’s!!) so I’m not really sure how much was “operator” fault and how much was the brush. I saw your great video on how to test a brush today…if you think it would be useful too you to see those tests on #8 I will do that and post the photo for you.
[Hey, if you haven’t seen it, check out Tonya’s instructive video on how to test a brush! https://www.scratchmadejournal.com/blog/watercolor-brushes-how-to-test-a-brush]