In your post #13 the path for the ground between C2 and the ground pins 4 and 9 is very long because the ground fill is broken up with multiple tracks cutting right across it. I can't even see how the ground gets from C2 to those pins, the actual route must be outside the image. @Paul_B has emphasised the need for short tracks, unless there is a short track for ground I cannot see on that image then you need to re-think the whole ground plane.