I had a very similar problem documented here (https://bugs.launchpad.net/subiquity/+bug/2033344), the recommendation of setting "remove_duplicate_entries" and "probe_additional_os" to False worked for me.
I had a very similar problem documented here (https:/ /bugs.launchpad .net/subiquity/ +bug/2033344), the recommendation of setting "remove_ duplicate_ entries" and "probe_ additional_ os" to False worked for me.