Problem: Specific Traffic is Missing
I see some traffic in the Web Sessions List, but some traffic (for example, from a specific program) seems to be missing.
Solution: Check for Traffic Filters
Check to see if any Traffic Filters are enabled.
If you've written or set any Fiddler Rules check those too.
Click Help > Troubleshoot Filters.... When you do so, traffic that would otherwise be hidden is instead shown in a strikethrough font. The Comments column will show which of Fiddler's filters was responsible for attempting to hide the traffic.