I recently imported 300+ users through juice into site that uses CB. (latest vertsions of CB and Joomla)
The problem i am having is CB dosnt display all the user accounts in the backend component User Manager. It shows up to 300 users and thats it. It dosnt matter if i set the diplay amount to 50 or leave it at 30, anything over 300 dosnt display.
I know the accounts exist because i am able to login to the site with them and when i try to manually re-create the accoumt i recieve an error stating that an account with that email already exists.
Of course i used the synch tool but that didnt fix the problem.
I had a similar problem (used my own tool not juice to load the users and they did not show) - look at the database tables #___core_acl_aro and #__core_acl_groups_aro_map and make sure your users are in those tables too