Trying to share folder "JasonAlerts" within mailbox operations to user u1.name

Issues:

1. Shared mailboxes do not appear under subscriptions in Thunderbird for another user

2. When I try to set permissions via IMAP commands I get in /var/log/dovecot.log

Aug 26 20:33:24 imap(operations): Error: nfs_flush_chown_uid: chown(/var/lib/dovecot/db) failed: Permission denied

3. The permissions for the file are:

root@dal-notify-01 Maildir]# ls -la /var/lib/dovecot/db/shared-mailboxes.db

-rw-rw-r--. 1 operations sharedusers 197 Aug 26 20:33 /var/lib/dovecot/db/shared-mailboxes.db

4. Users I'm testing with are part of the sharedusers group in /etc/group

5. IMAP commands DO write to the file:

[root@dal-notify-01 Maildir]# cat /var/lib/dovecot/db/shared-mailboxes.db

shared/shared-boxes/user/u1.name/u2.name

1

shared/shared-boxes/user/operations/u2.name

1

shared/shared-boxes/user/u1.name/operations

1

shared/shared-boxes/user/u1.name/operations

1

6. It will also write to the user's /home/operations/Maildir/.JasonAlert/dovecot-acl file

user=u1.name ilrw

However if I got into Thunderbird and try to subscribe, none of the shared folders are listed.  Can anyone help??  Thanks!!

Dovecot version = 2.2.10

dovecot -n

[root@server]# dovecot -n

# 2.2.10: /etc/dovecot/dovecot.conf

# OS: Linux 3.10.0-693.17.1.el7.x86_64 x86_64 CentOS Linux release 7.4.1708 (Core)

first_valid_uid = 100

listen = *

log_path = /var/log/dovecot.log

mail_debug = yes

mail_location = maildir:~/Maildir

mail_plugins = acl

mail_privileged_group = mail

mbox_write_locks = fcntl

namespace Private {

  hidden = no

  inbox = no

  list = no

  location =

  prefix = Private/

  separator = /

  type = private

}

namespace Public {

  hidden = no

  inbox = no

  list = no

  location = maildir:/var/mail/public

  prefix = Public/

  separator = /

  subscriptions = yes

  type = public

}

namespace Shared {

  hidden = no

  inbox = no

  list = yes

  location = maildir:/var/mail/%u:INDEXPVT=~/Maildir/%u

  prefix = shared/%u/

  separator = /

  subscriptions = yes

  type = shared

}

namespace inbox {

  inbox = yes

  location =

  mailbox Drafts {

    special_use = \Drafts

  }

  mailbox Junk {

    special_use = \Junk

  }

  mailbox Sent {

    special_use = \Sent

  }

  mailbox "Sent Messages" {

    special_use = \Sent

  }

  mailbox Trash {

    special_use = \Trash

  }

  prefix =

  separator = /

}

passdb {

  driver = pam

}

passdb {

  driver = pam

}

plugin {

  acl = vfile

  acl_shared_dict = file:/var/lib/dovecot/db/shared-mailboxes.db

}

protocols = imap

ssl_cert = </etc/pki/dovecot/certs/dovecot.pem

ssl_key = </etc/pki/dovecot/private/dovecot.pem

syslog_facility = local2

userdb {

  driver = passwd

}

userdb {

  driver = passwd

}

protocol imap {

  mail_plugins = acl imap_acl

}