I think he might did not recognize him because he was in a rush or something?
it was probably really something the company told him to do, to be formal and distant with AIM as much as possible, since that group in going thru rough patch and PAZE were only rookies, Shinwoo was frustrated and assumed the worst, can't really blame both of them
After Haeun debuted, he acted distant and formally towards Shinwoo in public due to orders/advice from the director of their company. While Haeun explained this to Shinwoo, Shinwoo misunderstood it as Haeun not wanting to associate with him (Shinwoo) due to his scandals (of smoking etc). This led to a crack in their relationship which probably resulted in Haeun not able to be there for Shinwoo along with the hectic schedule of his.
wait this makes me so sad though :( i really wanna know haeun’s reasoning for not being there for his friend siwoo when he was going thru a rough patch :/ like bro he’s ur friend, be a real one and at least talk to him like a real person