Business Time

Hi ben_hargreaves 

The error likely comes from how [Date] is used inside _DaysBetweenTable and _WorkingDays. DAX can get confused with column context in these cases, especially when comparing to the bank holiday table.

Try updating _WorkingDays like this:

VAR _WorkingDays =

    COUNTROWS (

        FILTER (

            ADDCOLUMNS (

                _DaysBetweenTable,

                "IsHoliday",

                    CALCULATE (

                        COUNTROWS('Bank Holidays'),

                        'Bank Holidays'[UK Bank Holidays] = [Date]

                    )

            ),

            [DayOfWeek] < 6 && [IsHoliday] = 0

        )

    )

This makes the holiday check more reliable.

To troubleshoot, try returning intermediate values (like _WorkingDays) to isolate the issue.

Let me know the exact error message if you're still stuck happy to help further

If this solution helps, please consider giving us Kudos and accepting it as the solution so that it may assist other members in the community
Thank you.