It sounds like the add-on script crashed. Sorry about that…
I just checked the error logs and saw a few crashes about 6 hours ago.
Part of the error is: (TYPE_INT32), "1/25/201" Invalid value at...
Is it possible you have some illegal date values in your spreadsheet?
Maybe start with a search for 1/25/201 (there might be more than one)?
If this doesn’t help, let me know.
Randy