We have many customers using DxDesigner to Allegro using several different options in the software. For example, this is supported if the design is created in a netlist flow or in the independent software release. It is not supported if designed as an Expedition flow with CES rules.
Please contact technical support at http://supportnet.mentor.com/ and open a support case for tracking. If you are not satisfied with the results, please contact me again.
Technical Marketing Engineer