Promotion by fixed price far more than set discount

I have a promotion code that is set to trigger a discount of a fixed amount, but when it is used, it discounts far more than expected unless the maximum discount amount is set to the same as the fixed discount amount.

For example, this promotion is set to discount by fixed with a set amount of "500", and a trigger value of "100"...

Discount: FIXEDAMT - $2,124.56
Subtotal: $41,238.35
Tax: $3,670.21
TOTAL: $44,908.56