Animation and Rigging Tools: FAQ, Known Issues and Feature Roadmap

Thanks for this great tool .
Need some help, maya 2016sp6.
Getting strange error when trying to export weights from character body mesh:
Scripts\ART_skeletonBuilder_UI.py line 10811: ‘NoneType’ object has no attribute ‘getitem
Also, cant go back to skeleton placement:
Scripts\ART_skeletonBuilder_UI.py line 11000: ‘NoneType’ object has no attribute ‘getitem
Can’t even tell when this is started to appear, everything worked fine before last save-load.