When a controller is in ‘extender’ mode, I think its stations’ sequential flags are ignored (I will check to confirm). This is because in extender mode, it’s supposed to be operated by a master controller, and it merely passively listens to command from the master controller. So if the zones on master controller are set as sequential, then the remote zones are also sequential; and if the zones on the master controller are not sequential, so are the remote zones.
You can turn off extender mode by typing in the IP address of your remote controller, go to Edit Options -> Advanced, and check of Extender mode. You can also do this on the controller physically by using buttons.