If a person directly affected tells you directly that someone is being racist, or sexist, or genderist, or ableist, or colonialist, or ageist, or sizeist, or displaying some other form of bias or bigotry, or that something is problematic along those lines and you "don't see it", two things are probably true. 1) you probably aren't looking carefully enough at the situation the person's telling you about 2) the person cares enough to tell you, this time, but will probably never trust you again with that feedback about that topic. So if you don't actively engage, learn, and make amends, they will probably never talk to you again about it. Not because they've given up. What they've done is give up on _you_. If that doesn't bother you, then honestly, I don't want to know you.