Water consumption is always key to egg laying (poop production).
put out extra waterers. If you are providing additive water (ACV, electrolytes, etc) then always have fresh plain water available in addition. Multiple sources so no one is bullied away.
you can also feed a mash: feed with water added to make a batter consistency. Sprinkle some seeds or other yummy treat on top to entice them. Mine like pretty wet/sloppy feed, but others say their flock likes it a little thicker.
How old are the birds? How many?
if they free range, could there be a secret nest somewhere?