The tool is ignoring the array partition directive because of the automatic optimization applied by the tool.
To perform the automatic optimization, the tool applies a global config option, as displayed below. Preview the config option and if not desired, either reduce the default option or remove it.
config_array_partition Description Specifies the default behavior for array partitioning. Syntax config_array_partition [OPTIONS] Options -auto_partition_threshold <int> Sets the threshold for partitioning arrays (including those without constant indexing). Arrays with fewer elements than the specified threshold limit are partitioned into individual elements, unless interface or core specification is applied on the array. The default is 4.