On Wed, 7 Feb 2018, Jürgen Spitzmüller wrote:
Well, it depends on the style file you use (in LyX: "Bibliography Style" in the BibTeX settings dialog).
Jürgen, A couple of documents ago I switched the style to authordate4, but this issue came up only late yesterday with the 2011 .lyx file. Perhaps something I changed in jabref caused it. Best regards, Rich