When attempting to test a project using XDKs App Preview on my mobile devices I get an alert
App Preview uses a different CLI version than the following CLI version in your project: 6.2.0
This is happening on my Galaxy Note 5 and Voyager Pro. I can simulate the project the fine using Intel XDK, but when trying to build the project it just builds forever.
The message from App Preview is there to alert you to the fact that what you are building against is different than what you are using in App Preview, so the test in App Preview may have different results than your built app.
I don't understand what you mean by "just builds forever," there is no build step associated with App Preview.
My first suggestion would be to update your Cordova CLI in XDK and convert the entire project. You can do this in the project build settings, where you can specify the CLI version you'd like your project to use. Also, make sure you have the newest version of XDK to match the newest version of Cordova.