Possible reasons:

1. Setting spot_bid_max_price = -1 is not accepted by Azure pools

Azure Databricks only accepts:

0 → on-demand only

positive numbers → max spot price

-1 is allowed in cluster policies, but not inside pools, so validation never completes.

2. Pools always override cluster policy spot settings

Instance pools always dictate:

VM type (Spot / On-demand)

spot bid price

node type

Cluster policies cannot override these.