Default value of the Relative Date type parameters gets changed once the user misses filling a mandatory field.
Steps to reproduce:
Due to defect DE39930
CA PPM 15.3, 15.4
The defect DE39930 has been fixed by the Development team and the fix is targeted to be ported in 15.4.1 Patch 1.
Patch 1 for PPM 15.4 Service Pack 1 will be released by the end of August 2018.