Tableau ISO week

https://en.wikipedia.org/wiki/Talk%3ASeven-day_week

Week in Tableau is not the european ISO week. Calculate it yourself in a variable

ROUND((DATEADD('day', 3, DATETRUNC('week',[Date]))-
DATEADD('day', 3, DATETRUNC('year', DATEADD('day', 3, DATETRUNC('week',[Date])))) +
DATEPART('weekday', DATEADD('day', 2, DATETRUNC('year', DATETRUNC('week',[Date]))))
-4) / 7 + 1,0)

Source: Falsche Wochennummer für europäische Gebietsschemata | Tableau Software