Opening about:support on Windows results in WebGL related errors
about:support on Windows results in the following output in the browser console:
Error: WebGL warning: Unable to restrict WebGL limits to minimums. Troubleshoot.jsm:525:18 Error: WebGL warning: Failed to create WebGL context: WebGL creation failed: * Troubleshoot.jsm:525:18
The suggestion is that ANGLE is broken. (Reported in our blog: https://blog.torproject.org/comment/275959#comment-275959).
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information