The EVOTAG App relies on your phones internet connection and location service. If any of them is not working correctly you may experience strange behaviour.
If your internet is not working or is unstable you may not see new Squads or Games, or updates to them.
If you location accuracy is really bad, placing you outside a Games boundaries, you will not see it in the nearby Game list or get notification to join games. Or you may be so far away from the nearby Users that they don't appear.