What worked for me:

- create the package with the wizard using "Do not save sensitive data";

- import the package to Visual Studio Management;

- right click on the package and "View Code";

- find the connection string, in my case Oracle:

<DTS:Property DTS:Name="ConnectionString">Data Source=Oracledb;User ID=userDB;Provider=MSDAORA.1;Persist Security Info=True;</DTS:Property></DTS:ConnectionManager></DTS:ObjectData></DTS:ConnectionManager>

- modify the string by adding "Password=userPassword"

- save the package;

In my case this eliminated the null password problem, not to mention that, the password in not visible in the connection string.

Hope it works for you!