Beam Joining Issue causes notes of the same value to join even when not selected to join

I am trying to adjust beaming in my engraving to join eighth notes within the same barline, eg joining four eighth notes under one beam instead of sets of two. It seems, if the note value next to the selected range is the same as the notes being selected to join, the beam will join ALL the notes of the same value, including those that were not selected to be joined, and even joining across barlines. I tried adding an empty measure between bars, then joining the notes as desired, but when I delete the blank measure, all the notes are joined again. This results in having to leave at least one note unjoined so that the other bars look correct. See the attached for example and to duplicate the issue.