The most likely reason that you cannot see anything in My Actions or My Assignments is because your Vault login is not correctly linked to your personnel record.
To resolve this, open your login details in User Authorisation on the Settings page, press the Find button, and select yourself. You'll now see your name in the Employee Name field.
Note: please follow these steps even if your name is in the Employee Name field already, as it may have previously been manually entered rather than using the Find button. Additionally, you may not have access to User Authorisation, in which case you will need to contact your Vault administrator for help with this.
Ensure that you press the Save button!
Check the My Actions or My Assignments tab again to see if your items are now showing. If there is still nothing showing, ensure that you have actions or assignments assigned to you.
If you have further trouble, please contact support, explain the problem, and provide one or two examples of items that should be showing in either of these tabs.