Why would my isa brown not lay eggs for more than 5 months? She’s young

[Yenny-Jen]

Hello. I have 3 isa browns that I raised from baby chicks. They started laying in June last yr. One if them laid xxl eggs and sometimes non shell eggs for 2 months but stopped and never laid again. Has been 5 almost 6 months and still.. no eggs from her.
Any clue why could this be happening? She acts, eats and drinks normal and is as active as the other ones

 

[nuthatched]

How have you confirmed she's not laying?
Most hens don't lay in winter, she likely went from fall molt to winter break.