Missing fields in select tool that are available in data set

[olivia0309]

I am trying to rename several fields in a data set when it is first imported into Alteryx using a select tool. 

This worked fine when I first ran the flow: 

However, when I import updated data, the select tool labels rows as "missing" that are still in the data set. The format of the data set did not change when I imported new data, the only new aspect was that rows were added. Does anyone know why data fields might be labeled as "missing" when they are still in the inputted file? 

[AkimasaKajitani]

Hi @olivia0309 ,

Are there little differences between from original file and the new file in the field names adding blank space, etc?

[Qiu]

t@olivia0309 
I also suspect that mght be some white space in the names of these "missing field".