MusicXML Export in OpenMusic: Redundant Clefs and Time Signatures

Hi,

While exporting a Voice or Poly-object from OpenMusic to MusicXML, I always get redundant Clefs and Time signatures in every bar if I open it in either Dorico or MuseScore. Only Finale cuts through the redundancy. All three, however, state that it’s not a valid MusicXML file and list some encoding errors. Is there a way to fix this from OM’s side?

Any hints or insights on this issue would be most welcome.

All the best,
António

PS: I’ve attached two screenshots of the same (and random) Voice-object in Dorico and MuseScore: