username change

i post art on my instagram account and i have been trying to change my username to something specific. i am aware of the person’s account who had been using my desired username, but i recently noticed that they changed their username to something else. i know instagram holds the username for 14 days after it is changed. it has now been over 2 weeks since i noticed them change their username, so it’s probably been even longer than that since they actually changed it. no one else is currently using the username as far as i can tell, but it still won’t allow me to change to it. i’m confused why i’m still unable to change to it. does anyone know why or how long i will have to wait until i can?