Hey guys, this is a known issue on amd64 based Umbrels. It will be solved with the next release. For now, here is a hot fix to be executed from your Umbrel root dir:
sed -i "s/bash/sh/g;" app-data/ride-the-lightning/rtl/entrypoint.sh && scripts/app stop ride-the-lightning && scripts/app start ride-the-lightning
Link to the fix to be merged: https://github.com/getumbrel/umbrel/pull/1115