Hi IliaSinev,

How are you doing today?, As per my understanding, You're right—Databricks doesn’t currently let you set Shared access mode on clusters that use instance pools, which is why you’re seeing that error with column masking and row-level filters. These security features only work when the cluster is in Shared mode, because it needs to know which user is running the query. Instance pools always use Assigned mode, so they’re not compatible with these features. The best workaround for now is to use a Shared all-purpose or job cluster (without a pool) just for the workloads that need masking or row filters. It’s not as fast to start, but it will work. Let me know if you want help setting that up!

Regards,

Brahma