Have you ever encountered this issue where in the rule package definition, when you try to add desired elements you don't see them in the prompt as shown below:
as you can see the element that you have defined isn't displayed in the prompt and this is related to your Global Payroll access. For instance, in this case I defined a country specific element for GBR but in my Global Payroll profile I have access to All Countries as shown below:
To resolve the issue, just change the flag to Specific Country and also select that particular country you defined the element for i.e. GBR in this case:
Now go back to the Rule Package definition, open the page again and try adding the element. If it doesn't work then log-out/log-in and then try again.