Yes. You could have cross-stave notes that were moved from the top staff to the lower one. These would behave the same as the pedal line.
The file is above in one of my comments. I have imported it as xml file. If it is possible to have notes from one staff in another, how can you see it and how can you fix it?
Ah, yes, sorry I hadn’t tried the file before. Copying and Pasting works as I expect: When I click to select the first bar of Piano L.H. and Command-click the one pedal line (Ctrl-click on Windows) to deselect it, then Alt-click on the Cello staff, the notes are copied. I tried selecting the whole L.H. part and filtering to deselect pedal lines, and Alt-click copied everything to the Cello.
I did not find any cross-staff notes in the file, so that’s not the issue. I did Edit > Select All and Edit > Notations > Cross Staff > Reset to Original Staff, and nothing moved.
Show voice colors.