I have been doing bird photography and importing hundreds of images, and I rely on Embedded Previews for my intial triage/culling. I have ALL of the options for replacing embedded previews disabled (Idle time, etc).
Yesterday, I imported 1400 photos into my Lr 11.2 catalog, and Lr built Standard Previews for every file.
Sometimes, it leaves me a few Embedded Previews, but this is maddening.
The Embedded Preview feature is ideal for those of us who need to triage quickly, including viewing images at 1:1.
Not sure if there's something I'm missing, or if this is a bug in Lr 11.
Jason P. Odell Photography www.luminescentphoto.com