autocomplete box in page restrictions finds deleted users, wrong usernames

We recently migrated our user management from JIRA to Crowd, our Confluence instance used to link to JIRA for authentication, and now links to Crowd.

We now found that, when editing the restrictions on individual pages, the autocomplete feature in that dialog acts strange:

• Users that have been deleted since the migration suddenly turn up in the drop-down box. Those users may however still be present in the internal user database of Confluence/JIRA, but that database shouldn't be used anymore since the move to Crowd. It's definitely not being used for authentication, so why does the autocomplete box still use it? When i select one of those users, It tells me the user can't be found, so it's purely an autocomplete issue.
• Our usernames have spaces in them, ie. 'joris vandermeersch' is my username. When I type 'jo' in the box, my username comes up as autocomplete suggestion, but when i select it, I get an error "Unknown user or group: joris+vandermeersch". When I type my name out fully in the box, then press enter, ignoring the autocomplete suggestions, my username is found correctly and added to the restrictions.

Are we doing something wrong in our configuration, or are these indeed bugs in the autocomplete system?