I don’t know for sure but I suspect this is reflective of the difference in permission set type (Functional vs End User role).  Is it possible that the roles being assigned are Functional roles and are therefore not in the table?

Checking our Apps10 environment I can see one user has 8 End User permission sets assigned, with 8 matching entries showing in that table, but the same user also has other Functional roles (in this case granted as child permission sets of the End User ones assigned directly) which do not show in the table.

Nick

Hi, in this table only End User permission sets are shown. Its happening when I am assigning a End User permission set to a user account (you can only assign an end user permission set to a user account).. Thanks for the response though. 

That is true, but you grant an End User role that contains other Functional Roles in the structure, which will not show up in the table.  I thought it might be useful to point that out in case that is what you were experiencing.

Also, permission sets can be switched back and forth between End User and Functional.  This means you can flip a permission set from Functional to End User, assign it to a user, then change it back to Functional.  I don’t know if those will show in the table after being changed to Functional after assigning to a user.