Could you tell us what kind of chip do you use?
Which IDE do you use?
I figured it. All the pins are selected. You have to “click off” so only one pin is selected. Clicking or double clicking on a pin when all are selected does NOTHING.
Once only one pin is selected, it works normally.
I spent all my time clicking off.
When actually I’d rather golf.
If you don’t fix the IDE,
And the programmers hide,
Your tools I'm afraid I must doff.