Does this happen every time you use it, a one time thing, or after using it for a bit?
It happens every single time I use it, and it's instant. The other two buttons related to watersport work just fine.
The real kicker is that if I were to play the game as usual and reach a climax through regular means, it also works perfectly fine. It's just this button that refuses to work.
In the meantime, I have disabled and re-enabled compatibility mode and I turned off MSAA (which I intentionally put on early on), but nope. Still the same. Event Viewer also doesn't seem to show anything.
In the next update, later today, it should be fixed. I replaced the functionality for the toggle button with a "Force Ejaculate" button. It basically sets the climax level to 100%, so it will happen naturally.
After I release the update (I can reply to the thread when it's out if you'd like), let me know whether or not it fixes it. There are some other bug fixes as well.