StartOfMonth Returns Second Day

[a68tbird]

Hello All -
I have a data model that I've added a MonthBeginning column that uses StartOfMonth to return the first date of the month. It works fine on 15 other months, except for May 2021. It's returning 2021-05-02. Any ideas why? I've added a screenshot here to show the abnormality.

 

[RoryA]

In spite of its name, that's not what that function does - unless you're using it on a complete date table. It will return the first available date in the column for the relevant month.

 

[a68tbird]

Huh - well, what do you know! Thanks for the reply!