IK failed, Manipulation plan failed at stage 'reachable & valid pose filter'

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I'm using MoveIt to control 4-DOF robotic arm I built myself. The first stage is documented here https://steemit.com/robot/@wintermute... I'm at the second stage now, where I'm trying to use Python API for pick and place pipeline. First the arm goes to the pre-grasp pose using set_pose_target command, which arm can execute 80 percent of the time. But pick operation always fails with following error:

Your environment

ROS Distro: [Kinetic]
OS Version: e.g. Ubuntu 16.04
Binary

Arm going to pre-grasp pose and then failing to execute all the grasps provided by grasp generator. A few guesses: 1)I saw people having issues with less than 6-DOF arms using KDL kinematics solver. I've tried Trac-IK with the same results. I also want to pay attention that my arm can move to different poses using RVIZ interactive markers, but the strange thing is, after joint2 or joint3 moved from the default angle I cannot rotate the robot platform(base_cylinder) with interactive markers anymore without swtiching on the "Allow approximate IK solutions" option. 2)There's no IK solver for gripper which is two revolute type joints. Can that be an issue?

I would appreciate any help, that could move me in the right direction.

Here are my URDF, SRDF and python code files.

https://pastebin.com/GfTVbmYa

https://pastebin.com/qiqfQwuG

https://pastebin.com/KDgVdAyG