MWO Mobile Integration Parameters

Hello,

We are looking to pass the work order # to another app / site to associate additional data with it. We are trying to build a link off of the work order in MWO
 

https://formsproapp.azurewebsites.net/launch?WorkOrder=${WO_NO}

Reading the documentation, it seems like this should be available.

However, when the link is executed the parameters are blank:
https://formsproapp.azurewebsites.net/launch?WorkOrder=

Thanks in advance for any insight you can provide!