Hi @Pat 

Your research on this is spot on! I was actually really curious about this problem and tested it in my own environment to find the exact solution, and I replicated your exact issue.

MV creation:

Sync to Postgres (Snapshot):

Here is exactly why this is happening and why you are seeing that error:

The issue comes down to the difference between Triggered and Snapshot sync modes for Lakebase Synced Tables:

• Snapshot Mode (Works): This performs a full refresh. It just reads the entire Materialized View as it exists right now and copies it over. It does not need to track incremental changes, which is why it succeeds perfectly.

• Triggered Mode (Fails): This performs an incremental sync. To do this, the background sync pipeline must use Change Data Feed (CDF) to figure out what changed in your MV.
  
  Hope this helps you get your Lakebase sync running!