I've noticed this add-on does not populate the most recent days (2 days) -- Is this an issue with the add-on or is it how Azure writes billing data?
This delay in collection is by design. Explanation:
Microsoft makes consumption/billing data available in 24 hour chunks. For instance, let's say I want all the data for September 1st. On September 2nd, data for September 1st can still be written. So, on September 3rd, we will collect data for September 1st. This is why you see the 2 day delay.