Playback Bug? - Tied note shared by Voices 1 & 2 plays untied

I have typeset Joplin's Gladiolus Rag and uploaded it to Musescore.com.

The playback of Bar 84 is playing the tied G flat as if untied. Gladiolus_Rag_with_Bar_Nos.mscz
Previous bars in the same strain e.g. 70, 74, 78, and 80 are playing correctly despite sharing a tied note between voices 1 and 2.
So this playback issue is unique to bar 84
It also occurs in the uploaded version https://musescore.com/user/58480/scores/1749906

Having originally created the score from an MusicXML file, I have recreated the RH of bars 70 and 84 manually yet the issue remains. Playback_Bug.mscz

The issue was there in Musescore 2.0.2 and also in the upload and I still have it in Musescore 2.0.3 in Linux running from AppImage.

I know I could tie the G flats of both voices and hide the superfluous tie but what is issue here?