TYPO3 Core

My flex form is running proper in admin context.

My flex form causes this error in user context:

Flex form displayCond on field "settings.flexform.pi1.ctrl.plugin.external.singlepid" on flex form sheet "ctrl" references a field or field / sheet combination "ctrl.settings.flexform.pi1.ctrl.plugin.single" that might be defined in given data structure but is not found in data values.

User has access to all tables and fields.

My flex form configuration

<settings.flexform.pi1.ctrl.plugin.single>
    <TCEforms>
        <exclude>1</exclude>
        <label>LLL:EXT:xblog/Resources/Private/Language/FlexForms/Base.xlf:sheet_ctrl.plugin.single</label>
        <onChange>reload</onChange>
        <config>
            <type>select</type>
            <foreign_table>tt_content</foreign_table>
            <foreign_table_where>list_type = 'xblog_pi1' ORDER BY title</foreign_table_where>
            <items type="array">
                <numIndex index="0" type="array">
                    <numIndex index="0">LLL:EXT:xblog/Resources/Private/Language/FlexForms/Base.xlf:sheet_ctrl.plugin.single.default</numIndex>
                    <numIndex index="1"></numIndex>
                </numIndex>
                <numIndex index="1" type="array">
                    <numIndex index="0">LLL:EXT:xblog/Resources/Private/Language/FlexForms/Base.xlf:sheet_ctrl.plugin.single.external</numIndex>
                    <numIndex index="1">-1</numIndex>
                </numIndex>
            </items>
            <maxitems>1</maxitems>
            <minitems>1</minitems>
            <size>1</size>
        </config>
    </TCEforms>
</settings.flexform.pi1.ctrl.plugin.single>
<settings.flexform.pi1.ctrl.plugin.external.singlepid>
    <TCEforms>
        <exclude>0</exclude>
        <label>LLL:EXT:xblog/Resources/Private/Language/FlexForms/Base.xlf:label.singlepid</label>
        <displayCond>FIELD:ctrl.settings.flexform.pi1.ctrl.plugin.single:=:-1</displayCond>
        <config>
            <type>group</type>
            <internal_type>db</internal_type>
            <allowed>pages</allowed>
            <size>1</size>
            <maxitems>1</maxitems>
            <minitems>0</minitems>
            <show_thumbs>1</show_thumbs>
            <wizards>
                <suggest>
                    <type>suggest</type>
                </suggest>
            </wizards>
            <eval>required</eval>
        </config>
    </TCEforms>
</settings.flexform.pi1.ctrl.plugin.external.singlepid>

I checked the issues

• https://forge.typo3.org/issues/80163

• https://forge.typo3.org/issues/79657

But they didn't solved my bug.

Do you have any idea, how to solve this bug?

Kind regards
Dirk