I've seen this before when you don't have your user that InsightIQ is using to access your cluster set up correctly.  For example, on each of my Isilon clusters, I created a "LOCAL:System" user called "insightiq" and added it to the "AuditAdmin" role (since that role has read-only privileges).  I specified this user in InsightIQ to monitor my Isilon cluster(s).  I believe if you create a user but don't assign it a role, you'll get the error you're seeing.  You should also make sure you have an NFS export for /ifs/.ifsvar/modules/fsa if you have removed the default /ifs NFS share.
I've upgraded to the latest version of InsightIQ--4.1.1.3 and tried using it to monitor a new isilon running OneFS 8.0.0.3.  Attempting to add the cluster produces the error:  "The Specified cluster is running an unsupported version of OneFS..." and directs me to the compatibility guide.  The compatibility guide does not list granular versions simply major 8.0.x and claims to support it.  Is this version not yet supported?
Does InsightIQ 4.1.1.3 not support OneFS 8.0.0.3?