It is the case. If they don't flip to flower on their own without giving them extended non-interrupted darkness, then it is either a mispackaged product (a photoperiod) or they didn't follow the basic procedure to breed autoflower seeds.
6 weeks is most likely not an autoflower if you don't see signs of flowering yet. Some "XL" autos are bred to maximize traits that prolong vege phase so you get a bigger plant.
These plants are relatively healthy, so i doubt stress is related. If they don't show pistils at terminal buds in th enext week or so, starting giving it 12h of uninterrupted darkness. You likely have a photoperiod that was mispackaged or the breeder fucked up something else in the process. Can only speculate.