Engrave Mode – Instrument Changes (hidden) don’t appear in Print Mode
When I edit some instrument changes in Engrave Mode → Instrument Changes → Hidden, they don’t appear in Print Mode.
It’s important to mention that I’m definitely working in the correct layout. Maybe it’s a bug?
What am I doing wrong? Please check the instrument: “Crn. ing.” “Corno inglés” (English horn)
Thanks!
In Layout Options, select the relevant layout in the Layouts list on the righthand side and check the settings in Players > Instrument Changes. If Show instrument change warnings is not checked, check it, click Apply, and see if that makes a difference.
Correct Layout was already selected, so that wasn’t the problem. 
Trying to understand—you say that hidden instrument changes don’t show in print mode, but looking at your screenshots, don’t you mean that hidden instrument changes do appear in print mode?
Can you upload your project file, or a cut down version that demonstrates the issue?
This is a really strange case… I tried many things without success.
The only temporary workaround I’ve found is this: disable condensing in the Layout Options, hide the instrument change label in Engrave Mode, switch to Print Mode, then re‑enable condensing. The label stays hidden.
But it’s not a very satisfying solution, because if you go back and forth again, it reappears.
Others might have better ideas!
It’s not just Print mode – if you switch to Write mode and then to Galley view and back to Page view, the hidden instrument change also reappears. Basically, I think anything that causes the page to be recalculated loses that Hidden property – but only when condensing is enabled.
And same with the Custom Text property (one of my attempts was to enter a space as custom text instead of hiding: same result).
Edit: Interesting: I just opened the file in Dorico 5, where you can’t hide the label but you can enter a space as custom text instead: this property isn’t lost, and it stays hidden in Print mode.
So this bug seems to be related to the introduction of the new Hide feature — which also interprets the old space‑hiding method by creating a signpost.
That being said, I did try to reproduce the OP’s issue in a blank project in D6 and I couldn’t… So it must be a very specific combination of parameters.