I'm using Mac so it says for the executable that "Apple cannot check it for malicious software." I think it means there is no developer certificate attached to the executable software.
I tried Safari-browser too. same thing than with Firefox. buttons don't register clicking nor hovering over them.
It maybe something to do with shaders. As my game doesn't work with the shaders on on chrome-browsers. luckily my game has toggle for this and it is not game-breaking to not have them on. just an extra feature. It is maybe related to that firefox can handle the GLES shaders or something and other browsers do it different and crash.