You can check what all the rules set for profile. Check if any rule caused the error.
select profile_name, rule_type, rule, clause, clause_option, status, users from DBA_LOCKDOWN_PROFILES;
Thanks, but there could be a lot of profiles with rules.
Is it possible to tell exactly which one catch action?
For this particular example you could re-enable the connections feature, test the login and if this is the desired disable feature, disable it again.
SQL> alter lockdown profile TZ_PROFILE disable feature = ('CONNECTIONS');
Now retest the connection:
If the user can now login, disable the feature.