Can't get key signature to show on custom staff

I’m trying to modify instruments.xml to get a three-line staff. I picked Alpenhorn, because, hey… why not.

I get three lines, but I can’t get a key signature to display on it. What am I missing?

Here’s what I have. All I changed was .

The treble clef isn’t displaying because I deleted it in the Music Symbols editor, but it’s a treble clef staff.

<InstrumentEntityDefinition>
				<name>3-Line Chant</name>
				<entityID>instrument.brass.alphorn.f.alias.alpenhorn</entityID>
				<parentEntityID/>
				<aliasOfEntityID>instrument.brass.alphorn.f</aliasOfEntityID>
				<inheritanceMask>0</inheritanceMask>
				<nameID>instrumentname.brass.alphorn.f.alias.alpenhorn</nameID>
				<numStaves>1</numStaves>
				<musicXMLSoundID>brass.alphorn</musicXMLSoundID>
				<numberingStyle>kDummy</numberingStyle>
				<showGuitarChords>false</showGuitarChords>
				<showChordSymbols>false</showChordSymbols>
				<staveDefinition>
					<numStaveLines>3</numStaveLines>
					<barlineSpan>1</barlineSpan>
					<useBrace>false</useBrace>
					<isVocalStave>false</isVocalStave>
					<defaultContextualStemDirectionIsUp>false</defaultContextualStemDirectionIsUp>
				</staveDefinition>
				<clefs>
					<clefIDsForEachStave array="true">
						<staveClefIDs>
							<idForTransposingLayouts>clef.treble</idForTransposingLayouts>
						</staveClefIDs>
					</clefIDsForEachStave>
				</clefs>
				<pitchedInstrumentData>
					<concertOctaveTransposition>0</concertOctaveTransposition>
					<transposedChromaticTransposition>0</transposedChromaticTransposition>
					<transposedDiatonicTransposition>0</transposedDiatonicTransposition>
					<useKeySignatures>true</useKeySignatures>
					<showTransposition>kFollowOptions</showTransposition>
				</pitchedInstrumentData>

And your hidden treble clef puts G on the center line of the three, I assume. So you want a flat on the top line as your F key signature. Interesting that the program will not comply. I wonder if the catch is the modified staff or hidden clef.

Is it possible you are seeing the Alpenhorn in its transposed state in which the sounding key of F would be written as C?

I thought of that, but I tried several other things: I tried it with a non-transposing instrument, I tried viewing in concert score, and I tried changing to other keys.

Sorry!!! I totally mis-read your FB post. For some reason I thought you wanted a 3-staff instrument, not 3-line staff, d’oh. I’m kinda stumped on this one too. I’ve only used 3-line staves for non-pitched stuff before. Finale gives you a lot more control over this but even exporting from Finale and importing into Dorico it loses the key signature.

Here’s a 3-line staff in F where the Bb should show on the center line. It imports correctly into Finale, but not Dorico. I’m guessing Dorico gets confused about how to define the staff and doesn’t know where to place the key sig. Not sure the best way to fix this other than graphically.
3LineF.zip (1.73 KB)

Thanks Todd. That’s what I ended up doing… I added a custom playing technique as a flat symbol and it works ok. I just have to check it for consistent spacing.