Playing excerpts

I opened a file created with Musecore 2 with Musescore 3 by selecting the existing folder

C:/Users/admin/Documents/MuseScore2/Partituren

as default folder in MS 3. Maybe this not recommnded, see other forum topics. Then opened a file in MS3.

When now playing excerpts, instruments can be heard, which are not displayed in the excerpt.
e.g.
excerpt is for guitar, tenorsax and trombone.

But audio plays Bb trumpet, acoustic bass and some other instruments of the complete score. I have to mute these instruments in the mixer, to hear only the instruments in the excerpt.

This behaviour did not show in Musesore 2, where only the instruments in the excerpt play.

What´s wrong?