Hey Growmie ...
This happens sometimes with autoflowers, I have dealt with it on two different occasions. It's like they forget they're autoflowers. But not to worry the way to fix it is by switching the plant to a 12/12 light schedule and within about 7 days you see it beginning to flower.
Hopefully, this was helpful and remember ..."Happy Growing" and "Free your mind one puff at a time"