@Pathoschild: upon testing, the mistake was mine and not UBPs. I had somehow left an extra space in an (integer?) data field separated by /-s, like this: "...144 1 0 /6/6", instead of "144 1 0/6/6". May I suggest that Content Patcher should do a little sanity-checking WRT white space? This kind of mistake is pretty easy to commit for a human, and, as it stands right now, rather time-consuming to catch.