power bi export to excel

i found the issue, and its a weird one. 

Basically, i have a time dimension, which has all time periods, except the oldest period because it falls outside of the rolling 12 months.

On the page, i have a time period slicer, which uses the time dimension, and the grid uses the time dimension. When i have no time periods selected, it shows the correct total at the bottom. However, if i manually choose the oldest date, which is not in the time dimension, it filters out the oldest period. that filtered value matches the export. when no periods are selected in the slider, the individual records do not equal the total at the bottom.

So, if i dont have any time periods selected on the time slider (set it to max and min), the total at the bottom shows the full number. However, the records for the oldest period are not in the grid because its outside of the range on the time dimension.

Basically, i think the export is more correct than the grid at this point because the total on the grid is not displaying the sum of the records, its showing the total amount of all records. 

I modified my slider to include all periods, including the oldest period outside of the rolling 12, and it matches exactly now. 

thank you to everyone for the help