Playback does not work properly in a specific case

Dear Doricorians,

In the following project, Playback does not work properly:
test trm (999 KB)
In the following screenshots, No. 3 works properly, but No. 1 and No 2 don’t.

No. 1 is the original state of Played durations.
In No. 2, I shortened the played duration the first note.
In No. 3, I shortened the notated note. Then the second note is played.

Could anyone explain why it occurs? It seems to be a bug to me, but there might be another reason which I do not know…