[#14191] - Style isBold="true" not working in a conditionalStyle

I'm using the Jasper Report library for Java v6.19.1 and the Report Design plugin for Eclipse.

I created this conditional style and I applied it to a text field.

<style name="myStyleBold">
<conditionalStyle>
<conditionExpression><![CDATA[$F{misura} == null]]></conditionExpression>
<style isBold="true" isItalic="true" isUnderline="true" isStrikeThrough="true"/>
</conditionalStyle>
</style>

All formats are working (isItalic="true" isUnderline="true" isStrikeThrough="true"), but the isBold="true" is never applied.