Issue:
Turning of the Environment in the Camera will also make the whole image (even your own Avatar) transparent in some worlds. It will also add a transparent layer on top of the whole image.
I could imagine Fog maybe causing but I can't 100% confirm this.
The world I had issues in was Midnight Rooftop (wrld_d29bb0d0-d268-42dc-8365-926f9d485505)
Attachments:
Here you can see the whole image being transparent: