Beamed Half Notes?

I am in the process of recreating a piano arrangement of The Blue Danube Waltzes in MuseScore and I am totally befuddled by the 22 measures of the Introduction where I see 6/8 time and what appear to the uninitiated (me) to be two dotted half notes with a triple beam.

I guessed a tremolo but that doesn't seem or sound right.

What am I seeing in these measures and how do I notate it in MuseScore?

A copy of it is attached.

Thanks in advance for the education!!