Hi, I have seen similar problems. Especially when I brought a bunch (10) of door/window sensors. I started adding a 3 or 4 and it took ages to synchronize and create xml file. Afterwards I took them one by one and waited until the process has ended. That means I repeatedly woke up the device until the xml was created.
Please notice that a lot of steps should pass before xml is created. If you restart OpenHAB it just starts from scratch until it eventually succeeds in creating an xml