Adding a bit to what 10thmtn suggested. It doesn't take much slide movement to set the striker on an XD. It takes about 1/2 to 3/4 inch travel to set the striker. So if the spend casing is being ejected and it is picking up a new round then it isn't an issue with limp wristing not allowing the striker to set. Unless he is pulling the trigger on the old spent casing.
If it is a good new round in the chamber it is something else. Might have just needed a good cleaning, could be hard primers.
Good luck, and hope all the kinks get worked out.