Export issues using ART. 'UNKNOWN_REF_NODE'

Not sure if the issue is with the plug-in itself or a deeper issue. when I display all the Joints, I find extra joints for the upper body. not sure why or how they got there? The main issue is I’m not able to export an FBX because of Deformation errors reading unable to find bind pose. Not sure why this is. The Model is animating along the Skeleton but when it comes to Export it starts reading off errors. I check the Export options, they’re set up the way they should its an error as far as I can tell with Referencing the model, skin definition or animation layers. any help on this would be greatly appreciated. Thank you so much for any time spent looking over the issue.