In the footer of FunnelFlux you will see a small link saying "clear tracking session".
What does this do?
Well, it purges your current session, which stores details about your entrances to funnels, country, ISP etc.
If you are testing the loading of funnel links (and not doing in private browsing mode), clearing the tracking session will allow you to force FunnelFlux to forget you and treat you as a new entrance/visitor.
This can be important for testing in scenarios such as:
You are trying to test conditions which are based on whether a user is tagged
You are trying to test funnels with conditions/PHP/JS nodes that read whether a person is a repeat visitor or new entrance
You are using a VPN to change country/IP and re-test links
In general, we'd recommend using private browsers for testing to limit how much caching and sessions interfere with unique tests.
Clear tracking session is just there to help you purge things to be sure.