TYPO3 Core

When you create a FlexForm with this field configuration for FAL:

<config>
    <type>inline</type>
    <foreign_table>sys_file_reference</foreign_table>
    <foreign_field>uid_foreign</foreign_field>
    <foreign_sortby>sorting_foreign</foreign_sortby>
    <foreign_table_field>tablenames</foreign_table_field>
    <foreign_match_fields>
        <fieldname>my_fieldname</fieldname>
    </foreign_match_fields>
    <foreign_label>uid_local</foreign_label>
    <foreign_selector>uid_local</foreign_selector>
    <overrideChildTca>
        <columns>
            <uid_local>
                <config>
                    <appearance>
                        <elementBrowserType>file</elementBrowserType>
                        <elementBrowserAllowed>gif,jpg,jpeg,tif,tiff,bmp,pcx,tga,png,pdf,ai,svg</elementBrowserAllowed>
                    </appearance>
                </config>
            </uid_local>
            <types type="array">
                <numIndex index="2">
                    <showitem>--palette--;LLL:EXT:lang/locallang_tca.xlf:sys_file_reference.imageoverlayPalette;imageoverlayPalette,--palette--;;filePalette</showitem>
                </numIndex>
            </types>
        </columns>
    </overrideChildTca>

    <minitems>0</minitems>
    <maxitems>99</maxitems>

    <appearance>
        <useSortable>1</useSortable>
        <headerThumbnail>
            <field>uid_local</field>
            <width>45c</width>
            <height>45</height>
        </headerThumbnail>

        <enabledControls>
            <info>1</info>
            <dragdrop>1</dragdrop>
            <hide>1</hide>
            <new>0</new>
            <sort>0</sort>
            <delete>1</delete>
        </enabledControls>

        <createNewRelationLinkTitle>LLL:EXT:frontend/Resources/Private/Language/locallang_ttc.xlf:images.addFileReference</createNewRelationLinkTitle>
    </appearance>

    <behaviour>
        <allowLanguageSynchronization>1</allowLanguageSynchronization>
    </behaviour>
</config>

You get the buttons to add or upload a file. Also uploading files work. But when you select a file, it does not appear in inline list. No errors in JavaScript console. No errors in AJAX calls. Maybe my configuration is wrong, but I've basically used the one from pages->media.