I've looked through the knowledge base, and found a couple references to halos shifting, but no solutions. I had not previously had this problem, but since I just upgraded to 10.5 now when I export to a PDF, regardless of settings, some of the halos shift out from under the text. Not all of them, and usually in one are of the map. If I export as an image that doesn't happen. I'm running ArcGIS on a new Windows 10 machine (should also mention that when everything was working fine it was also an older Windows 7 machine). So I'm not sure if it's the switch from 10.4 to 10.5, Windows 7 to 10, or something else. I included a screen grab to show what I mean about the shifting.