Crestron Toolbox versions 3.12.2 (3.1220.0018) and 3.12.2p1 (3.1221.0004) have a bug with device addressing from the Network Device Tree View tool (all devices at a Cresnet ID will be re-addressed when attempting to change the address of a single device)
Check the currently installed version of Toolbox by navigating to Help > About Crestron Toolbox... and upgrade or downgrade your installation as necessary, or use an alternate method of addressing devices