Applying lens blur changes image colour/contrast. It's glitchy.

When I apply lens blur using the lens blur module, the colours and contrast in my image change. It's glitchy and I can sometimes get the colours back by zooming in our out, toggling before/after view, changing from D to E module, or going into the crop tool. But it usually reverts again, and when I export the images to harddrive or Smugmug the colours are not what they should be.

Would appreaciate any help, with this error I can't use the lens blur module!