回複：n400 interview cancelled

this is just excuse. This is their policy change. Most likely because your name check is still pending. Because once interview done, it will trigger 1447(b), see article http://www.donkeyroad.com/womstatute.php

so now they no long interview naturalization applicant if name check is still pending to avoid legal issue

if you are sure that your name check is clear, then it is different story.