I just tried the ATTDEF and it works. Backing Sheet Attributes is shown in the I-Configure. However the generated iso failed to load content from the excel. Do you mind if you share your sample of PODProcessor.xml, PODProcessorSettings.xml, the excel file, and I-configure isometric directory sample for me to follow? Maybe I have do the wrong step somewhere, but I am not able to trace the error.

Or if you dont mind, I will PM you and share the files that I created to you in case you want to check it. Thanks.