It’s fixed by zooming in or out, which seems to reset the space allocation algorithm. ¯_(ツ)_/¯
Glyphs 2.4.1 on Sierra 10.12.4
Can y0u try the latest cutting edge version? (activate it in Preferences > Updates)
Cutting Edge version does fix it, but the UI is ungodly slow for me. Right side menu takes literally 3 seconds to open. 
I’ll stick to the non-beta version for now, it’s not a huge bug/deal. Just wanted to let you know!
Any plugins running?
Maybe delete and reinstall all plugins from the Plugin Manager.
Interesting, when I went to open Plugin Manager I was given this prompt: 
I thought it must’ve been the beta, but the most current public build (2.4.1) also had the same prompt. I’ve installed Git Command Line Tools on the new OS and cleared out most of my plug-ins. 2.4.2 feels snappier. 
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