Illegal capacity error reading child dataset field in index

Error reading the index thor_data400::key::avm_v2::20220627::medians_voctest on https://alpha-vault-thor-esp.risk.regn.net:18010/.

In BinaryRecordReader, when deducing the array size for the child dataset "history", the calculated array size is less than 0 and throws an illegal capacity error. (See attached screenshot.)  This is happening when parsing the first record.

In debug mode the field def len for history seems to be 4, even though the field def in the ecl watch view shows 16

Field def:

12 char fips_geo_12
8 char history_date
8 byte median_valuation
16 byte history
    8 char history_date
    8 byte median_valuation
8 byte _internal_fpos_