In Power BI, when counting rows in a table it is advised to use the COUNTROWS() DAX function instead of COUNT(). Use the COUNT() function only when you want to count the number of rows that do not have a blank value in the specified column.
Example:
Air Tickets = CALCULATE(
COUNTROWS('Air Ticket')
,USERELATIONSHIP('Calendar'[Date],'Air Ticket'[Issued Date])
)
Source: https://learn.microsoft.com/en-us/dax/best-practices/dax-countrows
