WebCanvas hardly reacting to clicks. Any workaround?

Hi,

The key component of one of my web apps is a canvas on which the user has to click to perform things. I developed it on Safari and it worked, so I continued that way.
Now that I’m testing it in the wild (outside of my Mac), I’m having troubles on other browsers, where clicks aren’t registered. So, on Windows, my app is currently unusable (and it’s the main OS where this app is supposed to be used).
It looks like Firefox, Chrome and Edge are seeing the canvas as a regular picture, offering the choice to save it (etc.); I can click however I want but won’t ever get a MouseDown event (even in a brand new project).

Is there a Javascript call which could help me in this case (i.e. capture a mouse button event and pass it to my app)? Or any workaround?