Have you tried the simple path (useful if you do not have to write a whole page of these rhythms) ?
In Write mode, select the notes you want to be beamed together, Ctrl-click and Beam together (or in the Edit menu, Beaming—>Beam together). Hope it helps !
I created a shortcut for beaming (cmd-b) and for breaking beams (alt-b) which I find very useful…
OS X 10.11.6, macbook pro retina Late 2013
Opera singer (lyric tenor), photographer, sound engineer, XeLaTeX user and a sometimes music engraver