[Samba] [Bug] Cannot create file but read/write is ok

[lampahome]

I don't know why I can't register bugzilla so I post here.

I have two ubuntu 16.04 machine A, B, and A install samba version 4.10.6,
and B install version 4.3.11.
I use samba-vfs in machine A.

I mount share of A in B ex:
sudo mount -t cifs -o username='ppp',password='admin' //IP/public
/home/ppp/test

And I found I can create file like $ touch test/yo
But I can read/write from existing files in /home/ppp/test

Here is smb.conf of A and I use samba-vfs module:
[global]

   workgroup = MYGROUP

   server string = Samba Server

   server role = standalone server

   log file = /usr/local/samba/var/log.%m

   max log size = 50

   dns proxy = no

[printers]
   comment = All Printers
   path = /usr/spool/samba
   browseable = no
   guest ok = no
   writable = no
   printable = yes

[public]
   path = /home/ppp/share
   available = yes
   valid users = ppp
   read only = no
   browseable = yes
   public = yes
   vfs objects = full_audit
   full_audit:prefix = [%U:%g@%I]
   full_audit:success = all
   full_audit:failure = all
   full_audit:facility = local7
   full_audit:priority = info

I found I can create file if I remove vfs variable and full_audit blabla.

Then I dig in and I found the %g will cause me fail to create file.

When I change from
full_audit:prefix = [%U:%g@%I]
to
full_audit:prefix = [%U:%I]

I can create file finally.

Anyone can help?