eCPM discrepancy?

A week ago I released my app, in that time I have racked up 1252 impressions (Video Starts), for the first 1000 impression my eCPM was $0, as expected after reading the Unity Ads FAQ, and once I reached 1000 impressions my eCPM started to rise, then, earlier today, when I was examining the graphs on my Unity Ads dashboard, I noticed the eCPM graph said $17.88, however when I look at the eCPM Box above the graphs it says I have and eCPM of only $2.76, which is still good considering it can take up to 5000 impressions to reach the average $6 - $12.
So I now have 2 variations of my eCPM $2.76 or $17.88, and I am not sure which one is correct, my first thought is that the eCPM in the box ($2.76) is the average over 7 days (this is not clear on the site) and that because for 5 of the days I was earning $0 then maybe the average would be that low, however when I did the maths ($7.69 [First day of eCPM based off graph]+ $17.88 [Second day of eCPM based off graph] / 7 [Numbers of days in a week]) the average shows up as $3.65 which does not match the $2.76 suggested by the possible 7 day average.

Now I really don't know what to think and have honestly no idea what my eCPM is at this point, so if you can explain this and give me some insight on what my actual eCPM is, that would be great, so thanks in advanced.

 

Please keep in mind, eCPM is number of revenue / impressions * 1000. When the eCPM is based on the last 7 days, only the data from the last 7 days is used. The eCPM can fluctuate wildly within small windows. Try expanding the window to span from the first day of release through today.