[Arch 4.2.3-1] Camera Upload permission denied but plex user can write to dir at shell

Camera Upload feature fails due to a permission problem. This is strange as I
can write to the directory in question when logged in as the 'plex' user at a
shell.

I created a directory to hold uploaded photos:

[root@vic vic]# ls -l /vic/pics/|grep bphone
  drwxrwxr-x  2 bry vic         27 Nov  1 10:56 bphone

The directory is writeable by the group 'vic', and the 'plex' user is a part of
that group:

[root@vic vic]# groups plex
  vic plex

When I try do do a Camera Upload, the logs show that the 'plex' user doesn't
have permissions to create files in that directory:

[root@vic Logs]# clear; grep bphone Plex\ Media\ Server.log|grep ERROR
  Nov 01, 2015 10:53:27 [0x7faad67f5700] ERROR - Exception handled: boost::filesystem::copy_file: Permission denied: "/tmp/fdb3-579c-f471-df92", "/vic/pics/bphone/IMG_3069.jpg"

When at a shell, I can create files in that folder as the plex user just fine:

[root@vic vic]# su -s /usr/bin/bash plex
  [plex@vic vic]$ touch /vic/pics/bphone/foobar
  [plex@vic vic]$ ls -l /vic/pics/bphone/foobar
  -rw-r--r-- 1 plex plex 0 Nov  1 11:03 /vic/pics/bphone/foobar

Why is the 'plex' user able to write to /vic/pics/bphone at the shell, but the
Camera Upload feature runs into a permission problem?

Some details:
iOS app v4.0.6
Plex Media Server v0.9.12.16.1509-1
Arch linux kernel 4.2.3-1-ARCH
/vic/pics is a zfs filesystem on a zpool with 2.1T free space.