FATAL Sugar Log Error due to field calculation

Hello,

I have a field named "transaction_marker_c".

It is used to check if the "Invoice Date" of a particular "Invoice" is before or after 2010 based off of formula:

ifElse(and(equal($transaction_type,"Invoice"),greaterThan(number(timestamp($invoice_date)),number(timestamp(date("12/31/2009"))))),"1","")

The field will populate a 1 if it after 2009 BUT the Sugar Logs tell me:

Tue Apr 30 19:04:27 2019 [19429][a20a60ac-5778-11e8-9f71-06d48441b777][FATAL] Exception evaluating expression in SetValueAction, ifElse(and(equal($transaction_type,"Invoice"),greaterThan(number(timestamp($invoice_date)),number(timestamp(date("12/31/2009"))))),"1","") : attempt to convert invalid value to date: 12/31/2009

I've attempted to alter the date format to multiple variations

(ex: 2009-12-31, 12-31-2009, 2009/12/31, etc.)

Regardless of the format, this error is throw for every record that has to calculate this formula.

I have also attempted to change the master date format in hopes to match it to what is in the above formula AND i've changed it back to default and retried all of the date combinations.

I'm stumped and since so many errors throw during mass update, it's preventing me from mass updating the 19k records that I need to get through.