I just spoke with Dr. Streete. He said that they are confirming faculty members for the ESI PREP program, and some advisers have not gotten back with their availability yet. If those advisers do not have availabilities, they will have to revisit students' applications. He said this process may, and likely will, go on into next week. To clarify, no interviews have been conducted for ESI PREP. He also noted that interviews for ESI PREP are more of a formality, as at that point an adviser has already agreed to work with a particular student.
It sounds like they have made a nearly final list of who they would like in the program, but cannot finalize it until faculty members report back. Side note - Imagine getting removed from the finalist list because a faculty member doesn't have availability!