Can I call qrexec-client-vm from a bubblewrap sandbox?

I want to sandbox an application using bubblewrap, everything but calling qrexec-client-vm works.
If I run qrexec-client-vm on it’s own and bind everything:
bwrap --bind / / qrexec-client-vm vault-disp custom.GimmePassword+account_name
I get a notification from dom0 saying it was allowed, but qrexec-client-vm errors with Data vchan connection failed.
Has anyone else been able to sandbox anything that requires qrexec-client-vm?