No custom depth export with sequencer

I have at the moment a huge problem with the custom depth export with sequencer. Perhaps it could be also a bug. I marked a moving object in my scene with custom depth (in the detail panel)

Then I exported my movie with sequencer (with the activated custom depth render pass)

But my images are all black. No custom depth is rendered. What could be responsible for this? I have no idea…

Best regards, Andreas