Error on apply Power Query: Expression in partition n/a in table n/a references an unknown entity

Hi everyone, thanks for the feedback here!

The "enhanced metadata format" preview feature does not yet support dynamic datasources, but we're working on it and expect it to be supported in the next month or so. A dynamic datasource is one where the query's source changes based on a function input, parameter, or, as is the case in the original post, a volatile function. This is why using the static source string succeeds. We are also working on improving these error messages to better identify what exactly is going wrong. 

A few other notes on the "enhanced metadata format" preview:

• Once you enable the preview feature, any report that is opened will be auto-upgraded to the new format. For now, while we're still in preview, if the upgrade fails it will silently fall back to the old format. Any new reports created with the feature enabled will automatically be generated in the new format. The upgrade is irreversible. We do save a backup of the pbix before upgrading, which you can find at "C:\Users\<user>\AppData\Local\Microsoft\Power BI Desktop\TempSaves\Backups". This won't have any of the changes you've made since upgrade, but might be a better starting point for you. Make sure you disable the preview feature before opening the backup file. 
• Previously, only tables that were loaded to the Report were persisted in the datamodel, but with this new format we save all queries to the datamodel even if they aren't loaded. This is why ImkeF hit the same error when applying changes even when all of the queries were not loaded as tables. 

While we understand that the current limitations of the new metadata format preview are blockers for some, we greatly appreciate each of you who have opted-in and are providing feedback. This new metatdata format will open the doors for many future modeling scenarios, and we're invested in making the upgrade as smooth as possible. If you experience other issues related to the "enhanced metadata format" preview, please reach out to me via DM or tag in a post.