tf_echo can find transform but waitForTransform can't

edit

For some reason, listening to the transforms between robot_center and laser_link from the network does not work anymore. In my Python script, I do:

self.tf_listener.waitForTransform("robot_center",
                                          "/base_front_laser_link",
                                          rospy.Time(0),
                                          rospy.Duration(5))

and get a timeout after 5 seconds. From the same terminal, when I run

rosrun tf tf_echo robot_center /base_front_laser_link

It works and I can see the transform. Both my laptop and the robot's computer's time are synchronized using NTP. Whan can be the reason for this behaviour?

EDIT:

I also tried running my script directly on the robot, still no difference, always timeout.

EDIT2:

I found out that a change was made recently in my robot where the static transforms are published with a time = 0.