Nute lock-out?

Thanks for letting me know your lighting specs ok, so here it is, amazon listing and it includes a PPFD map of the light for 12" and 18" https://www.amazon.ca/XP-2500-Samsung-Spectrum-Dimmable-Growing/dp/B093F89M2Q just the PDF map https://m.media-amazon.com/images/I/71di1BToWTL._AC_SL1500_.jpg your ideal PPFD is 700-900 µmol that's pretty much it at 18" but babies need a bit less. With that said. 18" should be good if the light is dimmed to 50%-60%, Slowly increase this lights power once the plants become bigger. should hit 100% by flowering time. Pay close attention to light stress like bleaching and crispy top leaves. If you see this the light needs to be raised or dimmed. When it goes into flower you will need to drop it down to 18/6 or 20/4 light cycle, the plants need a rest period. I've read some forms saying how their plants where experiencing issues in flower on 24/0, as soon as they gave them a resting period at night a lot of their issues went away. the issues where mainly plants looking tired and not well. It was also said that 18/6 produced the lowest yield but the best over all buds, tastes, smells, smoke quality. On 24/0 produced the most yield but the buds over all quality was sacrificed. 20/4 is a nice middle ground in between the two. They also concluded that vegging for the first few weeks with 24/0 was ok and did not affect the plant much at all. This is all based off of their findings and may not work 100% for you as all plants are different and you need to read their individual needs. It was also not communicated how low the lowest yield was or how big the biggest one was. So lower your light, 18-20" dim it down50-60%, and wait for your plants to respond. There lighting at 27" and 70% power is not strong enough. I'd also follow the advice about feeding from @gmslave, increase it when they start popping off. Good Luck,

@gmslave, I was wondering that myself. When I looked into the schedules that's what that nutrient line suggests for feeding of autos. never thought more of it. https://cdn.shopify.com/s/files/1/0549/4669/3369/files/Comp_Coco_10_Wk_Auto.pdf?v=1637614688 https://tpsnutrients.com/pages/feedcharts I would have hopped the manufactures would know the difference from photo to auto feedings, but hard to tell with new companies producing products, don't know what there own experience is in the field. I'd go with what @gmslave says as well as the light lowering. I found this link regarding feeding chats as well. the reference point was general hydroponics, but should transition over well to you situation. https://www.rollitup.org/t/autoflower-ppm-ranges.668207/

I think your LED is to high up, everything else in your grow is locked in! A+ man I'd Try and look on your lights manufactures webpage for a PAR map and PPFD numbers or a general lighting guidelines. If you cant find it, contact them via email. They should have this information. Or post your lights make and model and someone here may know of it. I use 300w Sunblaster led's and they sit any where from 20"-15" from my canopy. Once it gets closer they should start to green up faster. Keep us posted if this does not correct your issue. Cheers,