UV seams on metallic materials

Hello!  I've come across this issue multiple times and others have posted about it online, but still haven't been able to find a solution.  Attached is an image showing the issue.  A simple sphere divided into 3 uv islands, with a simple metallic material applied via cylindrical mapping (which should not have any visible seams).  Isolating the normal channel shows no seams, and actually none of the channels have any seams visible as one would expect.  However the material view shows clear seams where the uv islands meet.  Exporting maps and taking them into a separate rendering application results in the seams being visible just as in the substance material viewport.  "hiding the seams" isn't always possible, especially when dealing with large metallic surfaces that have to be divided into separate udims to produce an acceptable level of detail.  Please help!