Update: Rolled back to my custom AFCAD and all is well. So it's an AFCAD issue in P3Dv5
There are no problems with the AFCAD we supply with KIAH in P3D V5. See the attached screenshots, the first one showing all parking positions working as expected, the 2nd one in GSX, confirming the AFCAD in use is the one we supply with the scenery.
You probably must have introduced a conflict with your custom AFCAD, maybe they were both active.
You MUST use the latest AFCAD from FSDT in P3D V5, because the previous one (or your custom one, if it was based on the previous one), will surely cause visual problems because of the wrong exclusions that were made for the old ( new updated in V5 ) scenery from V4, which was based on data from 2006.