Np! I had an interesting bug that only showed up for me in the browser. Certain levels weren't loading but some were, seemingly at random. It turned out that the code that loaded the levels had the incorrect node(or scene) name. The capitalization was off ("Level1.scene" vs "level1.scene"). Godot didn't break in the editor on that, but when compiled for HTML5 it did break. It was a weird bug to figure out.
Idk if that's your issue, but it's weird that Cthulhu rendered fine for me.
Sadly I can't try it locally because I'm on mac.