This script is inside PlayerGui > SurfaceGui > TextButton
This doesn't work in first person. It does in third person.
SurfaceGui is adorned. This is a LocalScript. It is not Disabled.
script.Parent.MouseButton1Down:Connect(function() print("Button pressed!") end)

5 comments
If your in first person, your mouse stays in the middle of the screen. Go in third person in order to move your mouse around
I don't think it's possible to click in first person, by what I know.
@YBN_oSy I can still move my mouse around. My screen goes with it.
It seems that I had to click above the buttons, not on them...
Try to use modal.