Power Bi Refresh - Failing at last applied step

I have a report which runs automatic refreshes daily ,however every week or so it wont be able to refresh. Once I investigate the reason why it "breaks" it always givess an error message qouting the the last applied step in the transformation of the table. Please see below example.

Usually how I fix this is just go to "transform data" and refresh preview and close the transformation tab and refresh the dataset again. Just wondering what is causing this issue so I dont have to manually fix it every few days.