First, check to see if any doors are barring their way. If they are, make sure to open the doors by tapping on them.
If your crew members still won’t move, tap on their map icon to see if they are hiding. If they are, tap their map icon, then tap “COME OUT” on the drop down menu to the left.
When your crew sees the Xenomorph, they may run and hide without you telling them to do so. Alternatively, you can tell your crew to hide by tapping their map icon, then tapping “HIDE” on the drop-down menu. When a crew member hides, their map icon becomes a hollow circle instead of a full circle. While hiding, your crew will not execute orders until you tell them to come out. This allows you to tell a crew member where to go, then have them jump out of hiding when the Xenomorph is no longer a threat.