Hi 

I am trying to do a similar solution now. I can see from my alert that the value is there on submit, however it is not being written to the field.

Even if I go to the the Idea Management Portal scripted rest resource and try to just add a string it still doesn't write that either:

ideaInfo.u_test = 'my test';

  Did you also need to update IMCreateEditIdeaDataServiceSNC API?

Thanks

Mike