While I don't use the imputation tool and would accomplish this task with a simple formula tool, I noticed a quirk about the option for "Replace with value". It's a numeric up/down that doesn't allow negative numbers. Is that an oversight? Especially since in the "Incoming value to replace", if you choose "User specified value" it will let you pick negative numbers to replace - you just can't replace them with a specific negative number. It seems like the ranges on the 2 numeric up/downs should match. The top one ranges from -100000000.000 to 100000000.000, while the lower one ranges from 0 to 100000000000000000000.000, which is also incredibly larger than the upper bound for the first one
