Master section mute after deletion of 2.0 plugin in 5.1 mntg

Does anyone experience the same:

When inserting a stereo plug-in in the mastersection of a 5.1 audio montage and immediately deleting it, the master section causes playback to be impossible…only bypassing the mastersection makes the dialog:"Playback did not start successfully. This may be because:…" disappear.

Anyone experiencing this?
Thanks for sharing.

Niek/ Amsterdam.