one thing i just thought of that might be your problem is that some bluetooth devices only allow a certain amount of profiles to be stored on the device. meaning that some devices may remember 3 different connection it has connected to and it will just connect when they are near by. your headphones may only allow for 2 to be remembered. So you may need to completely remove them from the current devices and then try added them to the new ones. If that fails there should be a way to factory reset that will definitely remove any profiles that may be stored on them.
you may just need to google the model number and see how its done.