Device does not synchronize to its parent (master) clock if the parent clock is a boundary clock

In case the parent clock (master clock) is a boundary clock the measured mean path delay jitters much more than it does when the parent clock is also the grandmaster clock.
Due to the big jitter (which is normal) the measured mean path delay can become very big. The device then uses this big mean path delay to calculate the offset to the master clock which in turn becomes very inacurate as well. There are situation where the device will not synchronize to the master clock at all.