Moving Instrument Name text enables edit mode, but changes do not apply upon exiting edit mode

First reported by user tbdbitl at Editing Instrument Names , but I'm the one who just figured it out.

From the original post:

I add an instrument to an existing score, and then want to change the name of the instrument. I used the standard was of going into edit mode - double clicking on the text, or using Ctrl-E - and am placed in edit mode. I make the changes, and all looks good. Then I click outside the text area, and my changes disappear, and the text returns to its original format.

From my reply:

If you were able to get into edit mode at all by double-clicking an instrument name or using Ctrl+E, then that's the bug, because it shouldn't work that way.

Our conclusion was that either the user's computer had been under a demonic possession of some sort, or "software rot." But I have now figured out how to reproduce the bug.

Simply click and drag an instrument name. If you want, you can "Undo" the operation to put it back. It doesn't matter. Then, exactly as tbdbitl described, double-click the text. You're in edit mode. Click outside of the text box, and the changes are gone.