dbt compile works inconsistently

Hi, I often use the dbt compile tool and noticed that sometimes it does what I expect and spits out SQL in the window to the right, and sometimes it does not. And currently, it is not populating any SQL. Could anyone tell me what I need to do before I can see a query preview on the right-hand side? This is for a model that already exists and I did not write--I just want to play with the SQL in a SQL editor.

And I am saying "dbt compile" and "show query preview" interchangeably because I noticed both commands give me what I want...sometimes. But would love to know the difference as I'm sure there is one.