As the mentioned file in default UNA package has the following code in the 384th line:

<div class="bx-form-row-view-value">{$sValue}</div>

Little above the $sValue looks like:

$sValue = $this->genViewRowValue($aInput);

As this method returns the string, then for now, it looks like somthing wrong with the new field (Your category) and / or with Items list.