preserveFilenames() not working with SpatieMediaLibraryFileUpload

Hi, I'm using the

SpatieMediaLibraryFileUpload

SpatieMediaLibraryFileUpload

in a Form Builder. The docs say: "You may use the field in the same way as the original file upload field", however I can't get

preserveFilenames()

preserveFilenames()

to work. The uploaded files are always renamed - the instruction seems to get ignored completely. Is there anything I'm missing?