I don’t know what has caused this, or how to get rid of it. Any help would be appreciated.
Welcome to the forum @Roy_Helsing !
That orange highlight appears when you’re dragging a selection of notes around: either up/down to change pitch, right/left to move along the staff, or all over the place to move or copy to other staves.
It should go away if you press Esc.
That was my first try. - but ESC does not make it go away.
@Lillie_Harris could it possibly be a highlighted cue region?
No, it’s definitely the orange highlight you get when dragging a note up/down/left/right (new in Dorico 5).
It is not a cue - tried that also. I cannot highlight it, nothing happens if I click on it. If I delete the bar it is in it just stays in place over what bar replaces it. it contains one gray note. Have tried in both write and engrave modes.
If you close and reopen the project, hopefully you will find it disappears.