Moveit planning working perfectly through Rviz plugin but gives weird path through move group python interface

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I'm trying to move a robotic arm around obstacles. when I plan the path using rviz I get a very clean path that avoids the obstacles. when I plan using the move_group object I obtain a weird path and even fail sometimes to find a solution. I'm using RRTstar as a solver with the pathlength optimization. however when planning through move_group sometimes the solution is not the shortest path at all ! the arm follows weird trajectories and does unnecessary movements. any thoughts ?