I had a bunch of glyphs with a common naming element in their names; say, X: ‘X.kn’, ‘XHalf.kn’, ‘XmatraAa.kn’ and so on.
I wanted to change X to Y, so I typed X in the search bar to display all the glyphs with the name X in them. Since X was a large and specific enough nomenclature, only those glyphs showed.
I went along changing all X’s to Y’s and the glyphs consequently disappeared from the display window (because X had now gone from their names), until the final glyph. The moment I deleted the X and typed Y in the last glyph, the app crashed.
I’m using Glyphs 3.0.4 (3108).