If there is a journal enrty with a visible and a not visible detail then both details appear in the All and in the Activity tab. For example: user1 updates two fields, one is visible for user2 and other is not. This case both modification is visible in a single entry for user2.
If there is a journal enrty with a visible and a not visible detail then both details appear in the All and in the Activity tab. For example: user1 updates two fields, one is visible for user2 and other is not. This case both modification is visible in a single entry for user2.