Troubles with Samba protocol SMB2 and up

On a Pi with an installation with buster so samba 4.9.5, there is a folder:

drwxrws— 2 andrew family 4096 Nov 24 21:21 SharedRW

inside there are two files:

-rwxr–r-- 1 andrew family 0 Nov 23 19:51 andrew-file
-rwxr–r-- 1 wife family 1 Nov 24 21:05 wife-file

On the Pi [and all Pi], both users are a member of family

Locally: andrew can read file wife-file but cannot update it – this is as expected

the folder is shared using samba to the network:
[Shared]
comment = Shared
path = /media/HDD-Red/SharedRW
browseable = yes
read only = no
write list = @family
guest ok = yes
create mode = 0770
directory mode = 0770
vfs objects = dirsort

from a Windows computer, andrew can read file wife-file but cannot update it – this is as expected

from a linux Pi connecting with vers=1.0; andrew can read file wife-file but cannot update it – this is as expected

from a linux Pi connecting without vers=1.0; no one has permission to update anything and all files show ownership as root root, i.e. uid=0, gid=0

from a linux Pi connecting with uid=andrew,gid=family; andrew can read and update file wife-file – this is as wrong

Pi-bullseye [samba 4.13.13] cannot use vers=1.0, with good reason, but I want to be able to access the files on the shares correctly and I do not know how,

I would very much appreciate some assistance
Thank you,
Andrew

Did you add users to correct groups?

All users are a member of group family on all machines; it is my understanding that this is all that is needed, or have I missed something?

The references to Samba Groups I have found seem to reference AD/LDAP groups that I am not using, it is my understanding that this is not needed, or have I missed something here too?

Addendum, I have since set up a second machine running Bullseye and get exactly the same symptoms, so it does not appear to be a mismatch between Buster and Bullseye.