Affiliate plugin database query errors

We’re using Affiliate, which is producing lots of errors in our log file. Like this one:

“[21-Sep-2017 10:08:11 Australia/Melbourne] WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘%01.2f, now()) ON DUPLICATE KEY UPDATE uniques = uniques + 0, credits = credits ‘ at line 1 for query INSERT INTO wp_affiliatedata (user_id, period, uniques, credits, … “