I don’t know if you found the solution, but in case somebody has the same issue…
I had the same issue on some of my buttons but not on all.
I noticed the difference is that on some buttons I had a css property “padding-right:0px”.
I removed this and now all my buttons have a blue contour in Polyscope 5.
Great, that’s my problem also, I’ve removed the padding property and now it works.