ZigBee devices are connected but can't communicate if encryption is toggled off

We have a multi-node ZigBee network of Xbee modules and the USB PC XBee board.

The devices have the same PAN ID and Profile ID set up and in many cases the same Scan Channel mask. After they form the network they have
the same channel number and operating PAN ID, both full and 16-bit ones. All the devices can be easily discovered by XBee network discovery
API and they can communicate to each other via remote AT commands.

After enabling encryption on each of them, they continue to maintain the same network and can communicate to each other.

However, after disabling encryption they STOP communicating with each other while still maintaining ZigBee network. The fact they are on the same network can be verified by reading AT parameters one each of them locally. AT CH, OP and OI outputs are still the same. Even after issuing command sequence that make them
reconnect. e.g. change ZS to unrelated value and then restore it back, they are still unable to communicate.

The workaround has been to enable encryption back on each device, let them form the network and then disable encryption again. Only after this 2nd procedure do they start to communicate to each other again. Sometimes, but not every time, changing PAN ID on the whole network helps as well.

Again, this behavior is exhibited only after flipping encryption mode for the whole network in question.

QUESTION: Is there some condition in Digi firmware that doesn’t clear encryption status from the first try. The firmware revisions on the devices in question are 4059 and 4055. Is there another issue with our network setup?

You most likely simply need to issue a Global network reset so that a new network forms.