I have a partner I play with. But we are unable to enter as a group in zones like Delta Volanis, Hromi cluster, and Arcanis Arm. We have tried everything we can think of. Is this a zone design? Or is it a bug?
I think some of the missions in Delata Velonis are intended to be played singularly.
That being said, click M and select the option for choose instance. If you can join as a team, and you select the same instaned manually, then the only reason you would end up alone is if it's not a team map.