Bug #99388
closedRecord preview broken when first writable field is a FAL file field
0%
Description
When the TCA of a table is configured to display a FAL file field first or all fields before that FAL field are readonly then the preview won't work as expected. This is caused by the order of the data in the form POST request. The first entry in the data parameter will be sys_file_reference from the inline field. If the FAL field is not first then the first entry in the data parameter of the POST request will be from the actual TCA table.
This causes trouble in TYPO3\CMS\Backend\Controller\EditDocumentController::processData() when a preview is requested as the code uses the first entry of $this->data which will contain the form data as described above.
I ran into this problem with TYPO3 10.4. The code in 11.5 looks different so I don't know about that.