New mech doesnt drop to smallest sprockets

Hello bike community!

I am upgrading a Scott Scale 770 2014 to a 1x, and I got stuck on the rear mech setup. I installed a brand new Shimano Deore RD M5100, and it doesnt want to drop to the 2 smallest sprockets.

I checked the usual suspects:
– installation: the M5100 is a standard mount (direct attachment), meaning it should attach directly to the standard mech hanger with no B-link (https://bike.shimano.com/products/components/pdp.P-RD-M5100-SGS.html)
– B-screw: adjusted according to the specs on the largest sprocket, and I made sure the B-plate is installed between the hanger lip and the B-screw
– limit screws: those are almost all the way out, and are visibly not restricting the movement on the 3rd smallest sprocket
– cable tension: the cable is taut, not tight, and the same occurs with the cable unbolted
– chain: should not be too short, I sized the chain anew, according to Shimano specs (add 4 links)

Interestingly, the previous Shimano Deore RD-M610 SGS came with a B-link which seems like could help offset the 1-2 gears, but I havent tried, as I probably should not need it in the first place. Maybe that is the answer, that all internet and installation vids suggest against.

I am probably missing something super obvious here, or lucked out on a defective mech. I appreciate anyone pointing me in the right direction! This upgrade is a Christmas present for my girlfriend, who likes to ride along with me 🙂