The web exportable is a lower visual fidelity as the live Enscape / EXE files. This isn't a bug or known issue but rather the present limitation of web browser compute.
Yeah, i already knew the web quality would be lower than the live Enscape file. But I was more looking for a way to make the glass and floor look more like the live enscape file.
But the way I read your comment, it doesnt matter how I try and play with the materialisation in Revit, the end result will always be the same? (the end result being the pictures)