Import into SPICE failed, with "undefined exception"

I just tried to import a table into SPICE from an AWS MySQL database (via RDS). The end result is that all of the rows failed to import. This was the information that it gave me:

0% (0 rows) were skipped out of a total of 0 rows.

Skipped Rows
10001 rows where an undefined exception occurred.

I found this, but it’s not exactly helpful.

I downloaded the “error rows file”, but I have no idea how to interpret it. It just shows rows with the word “Undefined”. It doesn’t tell me, as far as I can tell, which column is causing a problem.

The data source is not invalid-- It’s coming from a MySQL database, not a CSV file.

How would I go about trying to fix this problem and get these records into Quicksight?

UNDEFINED error code co-relates to description - “An unknown error occurred while ingesting data.”