I created a table with 4 columns. I denied access to last column for a user named XYZ. Then i added 5th column. User can not access the 5th column as well. Why? If i as sysadmin use the command execute as user=XYZ i can access the 5th column. Why?
Now that we have a little more information, I have a theory for the possible cause. It's based on your comment that the results are different when you use a different client version. What is the data type of the new column? I remember a problem years ago when people were using a 2005 client and trying to access a table that included a column of type datetime2. Could this be a data type issue rather than a permission issue? Is it a CLR data type? Of course, if you tell me the new column is just a basic type like int or varchar(10), then I'm back to the drawing board for ideas.