Thanks for all the help and advice! In the end I had to do the following-
Organization>Create Network Templates
1-Create a new combined network Template named anything you want
2-Split the New Network Template I just created which then made 5 separate Appliance, Wireless, Switch, Cellular, Environmental templates appear
3-Delete Appliance and Wireless Templates (since I already had those attributes in my template)
4-Select Switch, Cellular, Environmental templates and the Existing Legacy Template
5-Select Combine Network Templates and use same name as used before. Save
The root issue was that the existing template was created before Environmental existed so it did not contain that attribute. I also went ahead and added Switch and Cellular just to have them in there if I ever need them.
Now all I do is unbind the network in question, assign the sensor then go back in and bind that network to the template again and it works.