I've installed 1.3.5. In my mailbox, the left hand pane indicates there are 48098 emails, which matches the number of files in /var/vmail/vhosts/domain/user/Maildir/cur of my Dovecot installation.
Page one of the view shows 1-50 of 48098 and there is a list of messages.
If I click to the next page, it show 51-100 of 48090, but the list is empty, and there is a message that pops up in the bottom right corner that says 'No messages found in this mailbox' (see attached).
I saw some other posts that suggested turning off caching. I didn't have caching enabled. For laughs, I enabled it, which neither hurt nor improved the situation. I disabled caching again, but this also had no affect.
Can you enable imap_debug and post the log for when you try and load the second page?
I managed to resolve it. Since this is a new server I'm migrating users to, I deleted the user from the roundcube and mail database, and deleted the user's directory in vmail. I then migrated everything back over with imapsync. It works now.