nope, nothing special when uploading 24-bit files. should be the same as 16-bit files.
the only difference is when you import it, you should choose "24-bit FLAC" instead of "FLAC" so that it doesn't try to make mp3 file derivatives, and also so that it shows up when people search for 24-bit shows. but it seems like you're not even getting that far, for some reason.