Tableau aggregates things, that's a lot of what it does. If you put Number of Records on the Label shelf you'll see which device IDs have more than 1 record being aggregated. That's where your "missing" records are going. If you look down in the lower left corner you'll see you have xx number of rows (something less than 69) and you will also see you that the SUM(Number of Records)=69.

What you'll need to do is use another field between the Location and the Device ID, a field that will prevent the Device ID from being aggregated, maybe an Order ID field (?) It just needs to be a field that isn't the same value for each of the Device IDs. If you don't have anything like this, go back to your Excel spreadsheet and create a new column that has a unique value for every record. Then bring the data back in and put this field between the Location and Device ID. Then you can hide this field by unchecking Show Header.

--Shawn