Booster: 2-way Messaging-Why would a recruiter not receive an email when a candidate replies?

We have Booster enabled, and have Twilio integrated within. We have been using this feature for a few years. Recently it was reported that there is a candidate that replied to a text, but the recruiter didn't receive any email/notification that there was a reply. It was in regard to also using the "reschedule interview" option as well.

The recruiter sent the "rescheduled interview" notification from the req/application. The candidate replied, but nothing came back to the recruiter. It looks like the notification went out as an email vs text (candidates preferred option). Could it have been the candidate seeing the email, yet responding via text?