I joined a team but it shows me as Not Participating. Why?

We already have an answer for a similar question which you can see here:
What does it mean when there is a "Not Participating" note under a teammate..

If you have more answers to add you can do that below.

If you join a team during a tourney you are not automatically able to participate, if you are a team member at the beginning of the tournament then you are able to participate

You have to join before the tournament starts.