I am not binding the columns because I'm using PDO fetch mode `FETCH_ASSOC` to cast the resulting object to an array.

Also I should've made this more clear, the exact same functionality works for all other IRIS queries I have. For example, the following query returns results properly:

SELECT Id, Name, Mnemonic, Type FROM Dict.VisitTypes;

Are there settings or anything configurable that could effect this on specific tables?