I copied the wrong debug data in my original post, it should be this:
--------> mailman3_router router <-------- 2023-05-22 05:13:59 115223 local_part=templist domain=sartrack.nz 2023-05-22 05:13:59 115223 checking domains 2023-05-22 05:13:59 115223 sartrack.nz in "sartrack.nz"? yes (matched "sartrack.nz") 2023-05-22 05:13:59 115223 data from lookup saved for cache for +mm_domains: key 'sartrack.nz' value 'sartrack.nz' 2023-05-22 05:13:59 115223 sartrack.nz in "+mm_domains"? yes (matched "+mm_domains") 2023-05-22 05:13:59 115223 checking require_files 2023-05-22 05:13:59 115223 file check: /var/lib/mailman3/lists/${local_part}@${domain} 2023-05-22 05:13:59 115223 expanded file: /var/lib/mailman3/lists/templist@sartrack.nz 2023-05-22 05:13:59 115223 stat() yielded -1 2023-05-22 05:13:59 115223 errno = 2 2023-05-22 05:13:59 115223 mailman3_router router skipped: file check