When adding new employee it is showing wrong effective date for core plan

Refer below steps to reproduced.

1]Suppose there is customization on core plan waiting period: 30 days. refer attached screen shots

2]add new employee through Ui with date of employment 01/01/2017.
3]Enroll now screen it is showing effective date 01/01/2017 refer attached screen shots.

4]Add new employee through Import with date of employment 01/01/2017.
5]Enroll now screen it is showing effective date 02/01/2017 refer attached screen shots.

through Ui It is not considering Waiting period of core plan showing incorrect effective date for core plan