Button OnClick Inspect changes

Agree with Spiney, but it also might be this issue: putting the actual script in the field rather than the script instance, which I have actually observed can sometimes have bizarre effects in the editor inspector onclick graphics, depending on Unity version.

Unity button onclick function script callback gameobject notes:

And just for completeness, the rest of my tips on hooking up these events…

For sliders and dropdowns and other value-returning UI elements:

And passing “more interesting” things when buttons are pressed: