Online program is not effective for a career switcher. And I've not seen success with HEC except as a means to develop a secondary transcript to help them get into a top school. I disagree you were chosen for interviews purely for the GMAT; I've had candidates chosen for interviews at top 15 schools with pretty awful test scores. At the same time, I've done ding analysis for those with high scores and no interviews.
My mind has to go to the obvious - your interviews! Either you came off the wrong way or failed to prepare properly, didn't show fit or a genuine interest. So many candidates get sloppy after getting an interview invite so maybe you did as well. This is what seems to make the most sense to me. I would work with a consultant to put together and update that might remedy some of this for the schools where you are waitlisted. Are you open to European schools? If so you might consider IMD or INSEAD J-term Round 2 or 3.
And applying next year is OK if you develop your goals and improve your on-paper and interview answers for the main questions: Why MBA (goals), Why You (connect the dots, show you are recruitable) and Why This School (fit.) Also, just as some general consolation, this season was very competitive, exceedingly so.
Would recommend that as an older applicant, you focus on one year programs, European programs and part-time programs.