If I import an Excel sheet with whole numbers and blank cells (either empty or ""), the detected type is Int64.Type without any errors and null in the blank cells. To my surrprise, even cells with a space or the text "null" are loaded as null in Power Query and these are empty in the data model.
Only if there is some other text in the cells, I get errors when loading the data with Int64.Type.
Maybe you can double check if there is no text in the cells that are loaded in error.
Also check for any unprintable characters using LEN in Excel or Text.Length in Power Query.
I am facing the same issue but in only 5 specific cells. When I reove the values, the error goes away. If I again put any values in those 5 cells, the error pops up again. I have wasted so much time trying to figure it out but nothing seems to work. I even created a completely new file and only pasted values in it but same error comes.
The excel file is available here. Need your help guys!!!