Filter on datetime column sometime work ,sometime not

khush19 , You expected output is not clear. Max on the row context as good as row values unless there is some logic added

Try

Total Calculated Amount =
var _max =MAXX(ParkingSessionSA,ParkingSessionSA[CurrentTime])
return
CALCULATE(sum(ParkingSessionSA[TotalAmount]),FILTER(ParkingSessionSA,ParkingSessionSA[CurrentTime]=_max))

Can you share sample data and sample output in a table format? Or a sample pbix after removing sensitive data.

khush19 First, not typing that data into an Enter Data query to mock this up, please post as text.

Second, what do you mean by the MAX of currenttime? If you have a measure and you put it in a visual along with currenttime column then if you get the MAX of the currenttime, you are getting that row's currenttime, which is already in context so you don't need to filter on it because that row in the table visualization and already filtered to that currenttime which is why your formula seems like it is equivalent to SUM([totalamount])

In other words, if I had data like:

Color

Red

Orange

Blue

And I create a measure like:

Measure = MAX([Color])

This would return the exact same thing as:

Measure = CALCULATE(MAX([Color]),FILTER('Table',[Color]=MAX([Color])))

So, should your measure work? Yes, but it is unnecessarily complicated.