Problem with Samba share with "Restrict write access to these users/groups"

I created a new share and I set “Restrict write access to these users/groups” option with: @group1, @group2, @group3

I can access the share but I can’t write even if I’m on group1. I have others share created with the same options and groups and I can use correctly.

With a testparm command I noticed that:

write list = “@group1, group2, @group3

OLD SHARE created months ago
write list = @group1 group2 @group3

Old share works, new share doesn’t work.

I manually modify with success with nano /etc/samba/shares.conf.d/newshare deleting “” and ,
I found that way, but if I need to modify again the share from Univention interface the problem come back.

Is it a bug?