Can't change External Editor

[hmelman]

Been using nvAlt for years, saves as txt files, syncs with Simplenote. Had the external editor set to Emacs, could use it fine from nvAlt. Got a new version of Emacs (renamed the old, saved the new with the old name Emacs.app). It's the default for opening .txt files and works fine that way. When I try to change the default External Editor in nvAlt preferences, I can choose Emacs.app but it doesn't stick. It could be an emacs problem, but it works opening files and dragging files onto its icon. If it is an emacs problem, what should I look for?

nvAlt 2.2.8 OS X 10.12.6, 3.4 GHz i7 iMac, 24GB RAM, 1TB Fusion