I’m getting 324 as well, attempting to use base64 and upload a single image.
It’s bizarre because the first time I ran the code this afternoon, it worked. All subsequent attempts now throw this “validations of media ids failed” code 324.
{ image: { w: 500, h: 500, image_type: 'image/jpeg' }, media_id: 596406498458267600, media_id_string: '596406498458267648', size: 57691 }