Martin,
I believe that this is currently being investigated for another user. I saw a reported issue where "DSM Editor override on identity specific properties are not appearing as expected in log activity", which sounds a lot like what you mentioned in your post.
I think you should probably get this logged as a case, if you haven't already. There was some testing going in the lab on our 7.4.2 Fix Pack 2 support boxes. A case would help us confirm though. If this is happening on a supported log source type, make sure you include that information and the steps that appear to cause the issue. Depending on your version, there might be a problem where the override for identity fields is causing an issue where QIDs are not lining up.
Log a case, if you haven't done so yet. Mention this forum post or link to this post in your case and mention XF-3193. This number will help Support reference this issue and might streamline your case when reviewed.
#QRadar#Support#SupportMigration