Since upgrading to RC1 from Beta4 on OSX 10.6.4 yesterday I'm experiencing various issues which all seem related to the read/unread status and count:
1. Randomly during the day, new messages will have come in and they won't show in ZD until I click Send/Receive which then 'instantly' displays them - almost like they were sitting there and the display simply wasn't updated (rather than them not being synced)
2. I view ZD and a number of inbox items are showing as unread (except I read them on my iphone say half an hour ago) - click Send/Receive and this refreshes the view (again instantly as per 1 above).
3. Despite having read all messages in the Inbox, the Inbox folder in the left view remains bold with a (1) in brackets - restart ZD the only way to clear this.
4. I sent an email, the email is sent, but the outbox count is not updated.
Todd's comments in this bug seem to match my experiences: Bug 44134 – lost new message notifications
*** Update ***
Since composing this post, ZD is now failing to show any new emails and neither the tree view or list view is display the new messages or count even after a Send/Receive.
More details: Before starting this post, ZD had been running all night - I experienced some of the above problems so I relaunched ZD, dealt with a few mails then started writing this post. I just logged into ZWC and noticed that various folders, including Inbox have new emails. I have clicked Send/Receive in ZD and it is not showing me the updates.
I am viewing by message with the reading pane at the bottom and 'Mark it read immediately' and 'Select the next message' are both selected in Prefs.