RBT didn't work

Hello. I'm new to dead by daylight. Only been playing for about a week. I was playing the pig after I found a glass shard (I main wraith). So I get into a round and toward the end I down two survivors. I put RBTs on both of them, and then let them crawl out to watch their heads explode. Now according to Official DBD Wiki, RBTs instantly kill you if you go beyond the exit gates and you have them on. However, the survivors crawled out safely and got away. Why is this? Was this a bug? What happened?