Hello, I'm behind a corporate proxy server and I had no issues with this until a couple of months ago. First I was using FoxyProxy, and one day I realized that Firefox wasn't syncing so I started troubleshooting (Troubleshoot mode) and found out that when a proxy addon (now I moved to SmartProxy and it's the same) is enabled Sync fails. I even tried setting up a new profile with a different, new, Firefox Sync account and the outcome is the same. Anyone else having this trouble? Is this a bug? Should I report it? Anyone wants to help me reproduce it? Thanks in advance!

PS: This happens on my Windows 10 machine too.