There might be two options for how this can occur:
Option1:
Only Seasonal Teams which are part of the "Panega Winter Season-setting" are shown. (See: How do 'Seasons' and 'Season switch' work? ) Every year, on June 1st, the Season setting is changed.
So, in order to see your seasonal teams in the new season setting, you must have created new seasonal teams for this new season too. How do I create a new 'Seasonal Team'?
Option2:
A user has changed the season of an existing seasonal team, to a non-active season-setting.
In this case, contact your Panega CSM.