Hi,
Could you please try
Clear the caches username-to-info, userid-to-name and nis-group-membership on all the nodes :
::*> diag secd cache clear -node <node1> -vserver <svm> -cache-name username-to-info
::*> diag secd cache clear -node <node1> -vserver <svm> -cache-name userid-to-name
::*> diag secd cache clear -node <node1> -vserver <svm> -cache-name nis-group-membership