Query Failure with undefined method 'gsub' for nil:NilClass

I am getting this error message on an explore when trying to pivot across a date type. This is the error I am receiving:

The dimension that I am trying to pivot on is set up like this in the view:
dimension_group: accounting_period {

    type: time

    timeframes: [

      raw,

      date,

      week,

      month,

      quarter,

      year

    ]

    convert_tz: no

    datatype: date

    sql: ${TABLE}.accountingPeriod ;;

  }

Any advice on what this error means here?