JFYI, yours is the second report I see in two days about some settings change that did not work until the device was rebooted (the other report was about completely unconnected to LTE settings), and I have seen a few in the past, I just added point #23 to my list here:
http://forum.mikrotik.com/t/gp-csa-for-mikrotik-devices/182176/1
I don’t think it is specific to new versions of the RoS, it is something that seemingly just happens when it is deemed to happen, not often, but it happens.
As I see it rebooting is anyway something that needs to be done when testing, as you really want to make sure that the device will work after a (be it accidental or intentional) reboot that will anyway happen before or later, so it is IMHO just something to add to the checklist of things to do when setting a device.