WebGL export using button on canvas does not fire click event using mouse

i tried to export a sample scene coming with some asset, where a list of buttons on a canvas should switch current animation of the model. this is working fine in standalone builds, but doesnt work in webgl. however the button click has visual feedback, it just doesn't seem to trigger the event, no matter if old or new input manager is used. this also is not related to the browser in use, as i see this behaviour in both firefox and chrome

this happens with 2020.2b9 (didn't test with former 202x.x builds), and works fine with the current 2019 LTS build