I also have a custom folder and a custom e-mail but they seam to sync ok with IMAP. But there are some options you can check.
if shown in WLM 2012 , right click the folder called "work" -> synchronisation settings -> be sure it is checked on to sync all.
OR
not shown at all in WLM 2012:
right click on your account
-show/hide maps
you will see a list of maps on the imap server , be sure work isn't hidden.
For the rest I have no clue , sadly and it is wait and see what microsoft is doing on their side.