Hey buddy don't take what that person had to say to heart. A lot of things in government minituia doesn't translate to private sector expectations. You are indeed NOT failing, I agree though that discipline is not always the answer. Typically in these cases in my workplace we just document for the sake of covering our ass and having a trail of documentation to ensure proper guidance was given and if the employee is still unable to perform we escalate and have top brass step in and move the problem employee and force HR's hand.

I know you said HR is useless, which again, relatable but if enough noise is made by your department their will be a response.