Eighth-note Tremolos

I must be missing something here. I’m trying to achieve the notation in the attached image (we’re in 2/4 time here), but I can’t get the outermost tremolo line to join the two eighth note stems. Instead, the beam between the two eighths disappears when I add the tremolo, making the two eighths appear to be two quarters. There’s an option in Engraving Options for joining the outermost line between two half note stems, but nothing for joining two eighth note stems (or stems of any other kind of note). Any help is greatly appreciated.
Eighth Note Tremolo.jpg

Dear Howard,
This must be related to the fact Daniel and his team have used some high quality sources (among which Gould’s Behind Bars) to implement the different notations as accurately as possible. Some notation options are not available because they appear to be not really elegant. It is thus quite difficult (or impossible) to reproduce some notations.

Aha! Thanks, Marc – you are absolutely correct. I even have Elaine Gould’s book and I remember seeing that before, but it leaked out of my brain. I will use the correct notation rather than trying to emulate old, incorrect notation.