I made the make proxy setting system-wide by editing the group policy. Now if I start Fiddler with any user, it captures the traffic from any session.
Some weird things that also happen(ed):
- I had to reinstall the Fiddler root certificate, most https sites were not working. This seems weird since this was working fine before, and I remember trusting the fiddler root certificate right after installing Fiddler.
- Sometimes Fiddler does not capture a session or a tab, this happens randomly. However, restarting Fiddler/ the browser fixes that.
But overall, it works.
Thank you very much for the support and suggestions!