I am writing a small widget that displays the time since I was awarded my last badge on Stack Overflow. I noticed that my most recent badge was missing from the timeline data (/users/{ids}/timeline).

After a bit more investigation, I found there are several badges that do not have a creation_date field, and these badges appear at the end of the returned data.

For example, when I run this query: /2.1/users/1367622/timeline?fromdate=1375920000&todate=1376006400&site=stackoverflow

I get:

{
  "items": [
    {
      "timeline_type": "badge",
      "user_id": 1367622,
      "badge_id": 83,
      "detail": "Fanatic"
    }
  ],
  "quota_remaining": 9951,
  "quota_max": 10000,
  "has_more": false
}

This is the correct date I was awarded the badge, however the creation_date field is missing. From looking at the doco, it was my understanding that the creation_date cannot be absent.

When I run this query to get all my timeline data: /2.1/users/1367622/timeline?page=3&pagesize=100&site=stackoverflow

the last items are:

{
  "creation_date": 1217540781,
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 2278,
  "detail": "Custodian"
},
{
  "creation_date": 1217540573,
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 2278,
  "detail": "Custodian"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 6,
  "detail": "Supporter"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 7,
  "detail": "Critic"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 8,
  "detail": "Citizen Patrol"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 9,
  "detail": "Autobiographer"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 13,
  "detail": "Yearling"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 31,
  "detail": "Commentator"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 32,
  "detail": "Civic Duty"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 71,
  "detail": "Enthusiast"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 83,
  "detail": "Fanatic"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 1306,
  "detail": "Analytical"
},
{
  "timeline_type": "badge",
  "user_id": 1367622,
  "badge_id": 2600,
  "detail": "Informed"
}

It appears that it is only user timeline objects with timeline_type "badge" that are missing the creation_date property, however there are items with an incorrect creation_date as well.

The top 2 items above do have a creation_date, but it is not correct. These two Custodian badges have creation_dates of 31/7/2008, but my timeline on Stack Overflow says they were actually awarded on 5/6/2013. I wasn't even a member of Stack Overflow in 2008, I joined in 2012!

Another example is this badge in my timeline:

{
  "creation_date": 1335872416,
  "post_type": "question",
  "timeline_type": "badge",
  "user_id": 1367622,
  "post_id": 10397150,
  "badge_id": 26,
  "title": "Infinite Scrolling - setContentOffset: stops deceleration of UIScrollView",
  "detail": "Popular Question"
},

This badge item contains all the necessary information, but the creation_date is the date I asked the original question, not the date I was awarded the badge.

I don't think this issue is just with badges either. For example, the same query includes this:

{
  "creation_date": 1254058162,
  "post_type": "question",
  "timeline_type": "revision",
  "user_id": 1367622,
  "post_id": 1483581,
  "title": "Get notified when UITableView has finished asking for data?",
  "detail": "Added code markers."
},

The creation_date returned is 27/9/2009, but the actual date for this revision was 17/6/2013.

Any ideas what's going on?