Why am I getting this message: Saving these changes will deactivate the Mobile Builder for this Form?

There are a number of features that are only available from the Advanced Form Builder or Builder BETA, like Reference Data and conditional logic, as well as further customizations you can make in the PDF Designer that are not available in the Mobile Builder.

Making changes to your form from the web based form builders or the PDF Designer will automatically disable the Mobile Builder for that specific form. 

You will still be able to use the Mobile Builder for other forms on your account.

Additional features, like Workflow and Dispatch, are also only accessible from the GoCanvas website and will disable the Mobile Builder when enabled.