TYPO3 Core

Hi, I have a flexform with some fields, one of they being this:

<category>
    <TCEforms>
        <label>LLL:EXT:cw_news/Resources/Private/Language/locallang.xlf:flexform.sNEWSFILTER.category</label>
        <config>
            <type>select</type>
            <renderType>selectTree</renderType>
            <size>10</size>
            <foreign_table>sys_category</foreign_table>
            <foreign_table_where>AND (sys_category.sys_language_uid = 0 OR sys_category.l10n_parent = 0) ORDER BY sys_category.sorting</foreign_table_where>
            <treeConfig type="array">
                <expandAll>true</expandAll>
                <parentField>parent</parentField>
                <appearance type="array">
                    <showHeader>true</showHeader>
                    <expandAll>true</expandAll>
                </appearance>
            </treeConfig>
            <autoSizeMax>10</autoSizeMax>
            <minitems>0</minitems>
            <maxitems>500</maxitems>
        </config>
    </TCEforms>
</category>

If I check a category and save, everything goes nice. But after saving, if I save again before the form is fully loaded (and the field not rendered yet), the data is lost.