Due to a new script creatures may, or may not attack you when you come too close while invisibile. If you are both invisibile and stealthed (and practically impossible to be seen/heard mechanic-wise) they will still attack you when you get too close; probably because the script just forces NPCs to attack (spell) 'Invisibile' people who come too close. - They do not attack stealthed people (yet, at least.)

Not yet resolved.

This remains a long-standing issue.