Guild Wars 2

Hello,
I might be missing something here from the mechanics, but it has already happen more than once with me and a friend.

When someone is contesting the capture point (trying to prevent a cap) even without being in stealth mode or leaving the point, the enemy team manages to capture it, how is this possible?

Thanks.

Any invuln effects stop contesting

Oh ok that makes sense, I thought only stealth would prevent it. Thanks.

Not any invuln, but select stuff.

Stealth
Mesmer Distortion
Ele invuln
Chrono Csplit
etc