Hello Sascha
There could lots of reasons why it’s not showing below
1. You might not have strong vram to display that
2. Make sure your files wrote out the channel data and your using that exact same name to read it back in on the rsVolume shader
3. It might be corrupted because it sounds like something went wrong with the VDB data grids.
Try a new download a test file
These should provide solutions to it or check the video tutorials below