After installing the latest TDM version 4.10, we executed a masking job for a small set of tables. The ADDDAYS() doesn't seems to be working.
SOURCE DB: ORACLE
Release : 4.10
Component : Web Portal - Data Masking
Below is a quick test with 2 rows of data:
Try changing the date to a valid date, such as 2000-01-01, and you should find the masking work.