Autoflower stays in beginning of flowering

I had a similar issue with a current grow I'm on. I'm NOT suggesting this if you care about the plant... BUT I stabbed the main a few times with tweezers over the course of a week to experiment. Seemed to get the hormones flowing in the right direction. Drilling a hole in it "flooded her basement" with hormones lol. I would check your DLI to make sure it's in range. Run your lights minimum 18hr on so you don't have to crank up the power just to give em the light they need. Looking at your pics, you still have a few weeks on the younger one. So there's still time for the older one to kick it in high gear. All plants are diff, even same strains from same parents. May be a "late bloomer" pheno the older one. Take the flower time from seed banks with a grain of salt. Exaggerated for "optimal" conditions and im sure they change to Bloom nutes as soon as a pistol pops (on autos).