I've had some issues with searches lately. I was searching for Mexico properties, Puerto Vallarta, or Cancun, for early-mid Dec/2023. At times the search turns up few properties, with "lowest price". But if I search for "AAA" or "Seniors", more properties come up. There are also times when few properties show up in morning search, then many properties show up in exactly the same search a few hours later.

So OP, you're not the only one experiencing Marriott searches not working too well. I've encountered numerous other problems, and Marriott reps said they don't have IT Dept.