if that doesn't help , it would be nice to see if there is any output in the console
*( mostly F12 on most browsers chrome or firefox, or ctrl+shift+i )
there should be an error report or log
it can be that your browser or your machine (gpu or the gpu drivers) doesn't support/recognize webgl2
guess that could happen also on older tablets or smrtphones
that also happens to me because i refuse to upgrade working hw :D but well that is me :)