email in shared folders not showing up with multiple backend servers

[Robert Spellman]

I'm in the process of moving users from back end servers running cyrus 
2.2.12 to 2.4.6.  Users who have been moved over can no longer see the 
content of shared folders if the shared folder resides on the 2.2.12 
server.  The front end and murder servers are still running 2.2.12.  The 
shared folders show up in Thunderbird when trying to subscribe to them, 
but they are greyed out in the "All Folders" pane, and the next time you 
go into subscribe, they are unchecked again.

Oddly enough, we are running imp for a webmail client, and they continue 
to see the content of the shared folders.

Here's my imapd.conf from the backend server:

configdirectory: /var/lib/imap
partition-default: /home/imap
defaultpartition: default
sievedir: /var/lib/imap/sieve
admins: cyrus
sasl_pwcheck_method: saslauthd
sasl_mech_list: PLAIN GSSAPI
proxyservers: backend

altnamespace: true
hashimapspool: true
allowallsubscribe: true
allowusermoves: true
autocreateinboxfolders: Trash|Sent|Junk
autosubscribeinboxfolders: Trash|Sent|Junk
autosubscribesharedfolders: shared.announce

tls_cert_file: /etc/pki/tls/certs/mailstore07.bates.edu-cert.pem
tls_key_file: /etc/pki/tls/certs/mailstore07.bates.edu-key.pem
tls_ca_file: /etc/pki/tls/certs/bates.edu-cert.pem

mupdate_server: murder.bates.edu
mupdate_username: backend

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