Hi @DW ,

I have replicated your scenario and encountered the same error when applying a column mask to a column named 1Y in Databricks SQL.

In short, it makes sense simply to follow Databricks documentation and use the SQL naming conventions, so that column names:

• Begin with a letter or an underscore.
• Contain only letters, digits, and underscores.

In my experience, using not standard column names, then the need to use ` backticks characters is asking oneself for trouble.