Assigning Shape Configuration to un-managed rebar shape causes ProStructures application to crash / freeze / hang.
1) Go to Start > Control Panel > Clock & Region
2) Now, in the Region settings, click to open the Additional settings.
3) Here, in the Numbers tab, you need to set the Decimal Symbol to , (comma) instead of . (dot)
4) After clicking on Apply & OK, start the ProStructures application and re-run positioning for the concrete & rebar elements in your file. This should resolve your issue and there should be no further crashes / freeze / hangs while working in the application.