Can't disable TMPro Buttons

I’m trying to disable two TMPro Buttons

I have them assigned in the inspector and I’m disabling them like this

 public void StartTimer()
    {
        addTimeButton.gameObject.SetActive(false);
        subtractTimeButton.gameObject.SetActive(false);
    }

But it doesn’t seem to work. I tried doing it different way but it also doesn’t work

public void StartTimer()
    {
        addTimeButton.interactable = false;
        addTimeButton.interactable = false;
    }

Any ideas what I’m doing wrong?

I found the solution. The syntax is fine, the problem was in TMPro files, after reimporting them and relaunching Unity it works fine!