MTC Not Waiting for Trajectory Execution Completion

[jtrubatch]

I am working with a UR3e arm with an RG2 gripper. When I execute the task the robot continues through the stages while the gripper is closing/opening rather than waiting for the gripper to complete it's execution.
From moveit_core/controller_manager/.../controller_manager.h

/** \brief Wait for the current execution to complete, or until the timeout is reached.
   *
   * Return true if the execution is complete (whether successful or not).
   * Return false if timeout was reached.
   * If timeout is -1 (default argument), wait until the execution is complete (no timeout). */
  virtual bool waitForExecution(const rclcpp::Duration& timeout = rclcpp::Duration::from_nanoseconds(-1)) = 0;

I tracked this down and it implies it is possible to set a timeout duration rather than waiting on completion. However, I am unsure how to access/set this within the context of MTC and if it is possible to set it specifically for the gripper and not globally. Is my reading of this correct and if so, how would I go about achieving this?