Mask fading in and out as black

Hi, I'm on the latest version of Adobe Premire Pro and trying to add a mask using the pen tool but the problem is whenever I apply the mask (inverted) to a .psd to show the video from the track below it turns out to be black in starting and in the ending of the clip. I also tried removing the crossfade transitions from all the clips but it's still black. I also tried the same in Adobe After Effects but the results are the same, This is driving me crazy. Please Help and check the screenshot. There are no keyframes applied to the clip either and this only appears at the start of the cilp and at the end of the clip. Is this a bug? Can't be as it's inside AE as well. Thanks.