One of the Payments has a check number of 61,969.40.

It could be a Customer Payment, Vendor Payment, Internal Transfer - it doesn't need to be a check.

Find it with this Filter:

If you are an Odoo.sh or Odoo On Premise Customer, use the following SQL to fix it:

update account_payment set check_number = Null where id = <id_of_the_payment>;