Here is the working solution to vxdiag multi tool (with serial number V71XN**** ) “RunCommand Error” after adding DoIP license to the vcx plus .
* JLR Pathfinder, Porsche Tester3, Benz or BMW DoIP license can be added to V71XN**** vcx plus scanner now.
The error was caused by low firmware version.
First run the firmware VCI patch here
Then update firmware in VX manager. It will work no problem.