When a user clicks on the All Tasks, My Tasks, and Available Tasks Views on the Home Page in Vault, the number of tasks in each view changes every time the views are switched. Why does this occur?
This can happen in Vault because Security and Permissions checks do not get applied to the different Tasks Views until the user physically clicks on each of them.
Example: The counts can change slightly if the user has any tasks on documents that they do not have View permission on. Security and Permissions check gets applied after the navigation.
Vault Home Page Documentation: About Vault Home