I'm trying to troubleshoot an issue with a dual-flush toilet, where every few days it starts making a noise like there is an internal leak.
I popped open the tank hood and found that it's continually draining. I brought over a plumber, but when he showed up everything was working fine.
Here's a video: https://photos.app.goo.gl/bri4xneT6kuVKrwv6
So I waited a few days and the noise came back! I brought the plumber again, and of course there's no noise anymore. I start flushing it over and over again to reproduce this issue, but no "luck".
What do I do?