I will say that as someone who did interview at columbia I'm also confused about their interview process but not convinced that no interview means rejection––mine was very chatty and not at all the tone I expected for a make-or-break type of interview. my advisor guessed the interviews have more to do with merit fellowships than with the decision to accept or reject. but possibly I just misread the room and it was a make-or-break interview, or possibly the entire process varies by subfield (and on the boards this year, all of the interviews posted seemed to be for 20th/21st century lit; the early modern interview was mine). I know this isn't a sure answer, but I hope the additional details about their interviews help put some minds at ease!