Why is cardinality Many:Many when a Excel table has a distinct field?

[Anonymous]

I decided to import a Table ("Workdays") from Excel with the number of work days. It has one row per YEAR_MONTH and the YEAR_MONTH field would be the connection to the BI_Calendar. This should be 1:Many. 

I read through pages of Cardinality questions and didn't find a similar one. I have this issue often when importing a table from Excel. Not when I make a table in SQL (I have no SQL access to do so). 

[amitchandak · Accepted solution]

@Anonymous , In table Workdays, is Year_month values are duplicate or null, in that case, you will have many to many

[Anonymous]

Blank Cells contained invisible characters. They show up in Excel as blank cells and Excel treated them as blank.

[Anonymous]

@amitchandak 

Thank you for your interest. No. Year_Month is distinct. I did an Export of the table from PBI. No Null Rows. I did a check of count for each row and Year_Month is distinct. Yes, the other two columns have many but that shouldn't matter.  The Forum wouldn't allow me to post the table output, odd.