Fellow writers: This is an unintended consequence of my changing the default dictionary engine from enchant to hunspell. I must have missed a step somewhere and want to learn what that was.
LyX-2.3.1 running here. Tools -> Preferences -> Language Settings -> Spellchecker has Spellchecker engine: Hunspell (found in /usr/bin/hunspell). I ran reconfigure after making the change but still no joy. A cluestick is needed. TIA, Rich