I have Windows 7 6bit. Fiddler 2 fresh install, no scripts, filters are off, https capturing/decryption enabled, certificate exported and installed/stored under Trusted Root Certification Authorities. Tried with Chrome and Firefox.
When I browse 2 sites from internet that both use https and are constantly communicating with fresh data (page itself is not fully reloaded, only data within) probably with jQuery/API in JSON/XML format from the server then one site data communication is captured and the other not. I captured same site data communication over the year ago with success and without any tricks (except allowing https capture/decryption in Fiddler). From visible side the site has not changed.
If anyone interested testing then:
go to LIVEBET, pick one ongoing event and wait the data communication (red/green arrows will appear)
I am very thankful for any hint.