scriptJob execution when playback stops

Hi, i basically setup a scriptJob with attributeChange on enum for matching IK/FK for left arm. It works fine at the viewport but it's not behaving as i'd expect to when i try to animate it. I'm probably missing something but couldn't find what it is. Here is the video of what's happening:

https://gfycat.com/WellwornEvergreenAdder

The code example just for the left arm:

myCode = '''from maya import cmds, OpenMaya
def leftArmMatch(*arg):

            #IK TO FK
            if cmds.getAttr('arm_L_settings_CTRL.IK') == 10 :
                cmds.matchTransform('arm_L_Shoulder_FK_CTRL', 'arm_L_Shoulder_bind_JNT')
                cmds.matchTransform('arm_L_Elbow_FK_CTRL', 'arm_L_Elbow_bind_JNT')
                cmds.matchTransform('arm_L_Wrist_FK_CTRL', 'arm_L_Wrist_bind_JNT')

                cmds.setAttr('arm_L_settings_CTRL.IK', 0)
            #FK TO IK
            else:
                startJnt = 'arm_L_Shoulder_bind_JNT'
                midJnt = 'arm_L_Elbow_bind_JNT'
                endJnt = 'arm_L_Wrist_bind_JNT'

                start = cmds.xform(startJnt ,q= 1 ,ws = 1,t =1 )
                mid = cmds.xform(midJnt ,q= 1 ,ws = 1,t =1 )
                end = cmds.xform(endJnt ,q= 1 ,ws = 1,t =1 )

                startV = OpenMaya.MVector(start[0] ,start[1],start[2])
                midV = OpenMaya.MVector(mid[0] ,mid[1],mid[2])
                endV = OpenMaya.MVector(end[0] ,end[1],end[2])

                startEnd = endV - startV
                startMid = midV - startV

                dotP = startMid * startEnd
                proj = float(dotP) / float(startEnd.length())
                startEndN = startEnd.normal()
                projV = startEndN * proj

                arrowV = startMid - projV
                arrowV*= 1
                finalV = arrowV + midV

                pv = 'arm_L_Elbow_PV_CTRL'
                cmds.xform(pv , ws =1 , t= (finalV.x , finalV.y ,finalV.z))


                cmds.matchTransform('arm_L_Wrist_IK_CTRL', 'arm_L_Wrist_bind_JNT')

                cmds.setAttr('arm_L_settings_CTRL.IK', 10)

cmds.scriptJob(attributeChange=['arm_L_settings_CTRL.match', leftArmMatch])

#scriptNode

cmds.scriptNode(st=2, bs=myCode.replace("'''", "''"), n='matchScriptNode', stp='python')