EasyAdminBundle transliterator_transliterate error for file uploads

I have an EasyAdmin form field setup in easy_admin.yaml:

- { property: 'imageFile', type: 'file_upload', type_options: { upload_dir: 'public/data/gallery/images/', upload_filename: '[uuid]-[timestamp].[extension]'}}

When I try to upload a file I get an error:

Attempted to call function "transliterator_transliterate" from namespace "EasyCorp\Bundle\EasyAdminBundle\Form\Type".

If I remove this part - it works fine:

upload_filename: '[uuid]-[timestamp].[extension]'

What is wrong with this part of the config?