Antispoofing is configured on the Cluster Object > Topology Tab - The Antispoof settings are shown when you select "Edit Topology" here is an example:
EXAMPLE ONLY FROM DEMO MODE OF SMARTDASHBOARD 
The Antispoof settings are indicated in the Topology Column on the Right Side.
It is a lot easier to offer advice if you put in a screen shot of your current Topology that will show us what your antispoof settings currently are.
As I asked in my previous post this can be done by...
Any chance you could screenshot the Topology Tab of your Cluster Object.
In particular, I mean SmartDashboard go to your Cluster Object > Topology > Edit Topology - take screenshot (ALT>Print Screen).
As an aside, and nothing to do with your original question - the two sync nets you have shouldn't normally be specified as Cluster interfaces - I think it is more normal to specify these only as sync interfaces (1st Sync and 2nd Sync).
What type of clustering are you using? VRRP?