Provide Hint that no Type-level operation is present

[thorsten-reitz]

Based on user feedback, a misunderstanding that occurs occasionally is that users miss the need to create a type-level operation, such as retype, merge or join. Users create property-level cells and don't get any transformed results.

Suggestion: If a user first created property-level cells, add a warning to the Report view that a Type level operation is required for the transformation to execute.

[thorsten-reitz]

Estimated Effort: 8h