SYMPTOM:
It is currently not possible to search for all facts with extensions and/or degradations using the Search Editor in Strategy Developer.
However, an enhancement request has been logged in order to provide users with the ability to search for only those facts with extensions and/or degradations via the Search Editor.
ACTION:
This issue was reviewed by our Technology team for feasibility and will not be scoped for a code fix in any upcoming Strategy release.
WORKAROUND:
To workaround this limitation, use the Project Documentation Wizard to generate a report on the Fact (Schema) Object Type, as shown below:

This will generate report documentation on all the facts (including extensions and/or degradations) for a selected project, as shown below:
