I set up a cnPilot E500 and a cnPilot E400 and onboarded them on cnMaestro.
cnMaestro shows that the devices where successfully onboarded and they are online but when I change the settings on cnMaestro, it doesn't synchronise with the devices.
In the status, it shows the message "Not In Sync: Failed to push configuration to device"
That depends on the SKU of your e410s. Some SKUs support different sub-sets of available country codes.
Log in to one of your devices via its web UI, navigate to Configure > System and check the list of countries in the Country-Code drop down. This list is what country codes may be accepted by your devices.