So I have an issue and maybe it is a known issue. The Distance on the Daily Steps line is including both the 3.01 and what I would guess as the 1.52 from the 2986 steps showing a total of 4.53 miles. Basically it is double counting the run distance which is also included in the totals. The total value should be 20.58 and not 23.59. Is this a known issue, are other people having the same issue.
The steps actually look fine. The 5k+ steps are from the 3 mile run and that looked correct at time. The other steps for the day were 2986 and those look good As well. When I look at my Fenix 3 history it looks good as well. It is showing 8830 steps and 4.8 miles. I really think its problem with GarminConnect.
If it's the Fenix 3, it does actually sound like a bug.
Perhaps it would be a good idea to log the bug at Garmin Support since you have it narrowed down very well. I did that on the support site with a report bug I found and they called me about it within 10 minutes.
It was actually doing the same thing with my 920XT as well. To me it is a garmin connect issue on the Activity tab of the daily step dashboard. Again you can see the example in the screenshot that I listed above. I am assuming it is a common thing and I would guess it is already been reported but I haven't seen it anywhere. I opened a support issue as well.