Marketo's ID is one of the selected columns, but it's good to know that I should always include it.  Thanks!
The change didn't skip me to another page - the data just disappeared!  (Hey Presto!)
The columns I selected are custom, (set up as True/False), and I've been populating them with imported "trues"; some columns are all null.  Do you think I should populate the null spaces with "false" using a flow action?  (Ack!)
Thank you all for the assistance!