Symptoms
When adding the K2 app to SP list or library and creating the forms, I get a new item or new document form and view created, but I cannot select the K2 new document form from the Forms Settings screen in the app. This option is always grayed out? How can I configured a document library specifically so that I can use a K2 form for the new document process?
Diagnoses
Confirmed that this is by design. At some point these options were not greyed out/disabled and there were request to disable them which has been implemented. This has been disabled because it used to create confusion leading the users to assume on the Form Settings Page for a Document Library that K2 will provide the option of using a New Form - which is not the case.
Resolution
This is by design to see the 'Create new Item, use...' setting in the Manage Form Settings screen, as disabled. It is disabled because it created confusion that the user assumes on the Form Settings Page for a Document Library - that K2 will provide the option of using a New Form - which is not the case.