Thanks for that azygous. I was just searching the forums for "no shell" and came upon this. Apologies to the op for leaping in like this. ..
I actually watched one of my hens pass a shell-less egg just a few minutes ago and did some checks. She's acting fine, eating, drinking -- but I'll still do the tums trick in a minute.
I've been adjusting coop lighting times to keep up with the rapidly shortening lod and have a strong suspicion that is the cause. She laid this am but her egg was a bit misshapen. I asked her what happened but she's clammed up! Blasted bird.