Data.get_mut() returns an empty slice

Trying to get the raw video data from a Data struct via get_mut() returns a &mut [u8] with expected length (height x width x 4, apparently), but without any contents.

Looking at https://gitlab.freedesktop.org/pipewire/pipewire-rs/-/blob/main/pipewire/src/data.rs, I tried appending this line : println!("{:?}", self.0.data as *mut u8); to the get_mut function, and it seems to always return 0x0

Please let me know if more explanation or code is required.