I am having trouble adding an updated forecast to my cost source. Not sure why, but when the file is imported, it doesn't just add the headers. It adds 4 columns; A, B, C, and D. With that. none of my formulas work.

Hi Darragh!  Do you see the checkbox option to indicate that your data has headers?  

Check that and see if that doesn't fix it for you.

Jenny, yes that was selected, yet my headers would still not import. 

I'm having the same issue with another file!

Is your data set up with any spaces in between the headers and the data - sometimes that stops the data loading as expected in R12, I learnt that the hard way