@RenataC5

You can’t put a Declare Index on pyCorrPage sitting under User Pages because it is a transient clipboard page, not a persisted property on a class. The practical fix is to mirror only the fields you need into a Page List on your work class and index that list. Create Index-MyApp-Corr mapped to pr_index_custom and expose just the columns you care about. Add a .CorrRefs Page List on your Work- class pointing to the relevant Data-Corr class, and create a Declare Index rule on .CorrRefs that stores pxInsIndexedKey of the parent case plus your selected corr fields. Populate .CorrRefs at the moment you create or send correspondence using a post-processing data transform or activity, so runtime impact stays minimal. For existing cases, run a one-time job scheduler to backfill the list, then rebuild indexes. Build your Report Definitions on the Index class and join to the case by pxInsIndexedKey if needed. If you truly cannot touch the work object, use a Declare Trigger on the Data-Corr class to write to a separate reporting table instead.