I’ve been having problems with copy/paste not working in the 1.3.x and 1.4.x versions of Glyphs. Copy/paste work at first, but after doing some work in a tab I can neither copy or paste. This problem affects both outlines and the glyphs themselves; when the problem occurs I cannot copy words to and from tabs in Glyphs. Opening a new tab fixes the problem for a few minutes, and then it occurs again.
Do you see anything in the console.app?
Nothing is showing up in the console. I’ve also noticed similar behavior that prevents me from entering sample text.