If you add a Discussion module to a course backed by split mongo, the "Discussion ID" it displays will change every time you refresh the page - until you've made and saved an edit to the discussion module (such as setting its display_name).
This is inconsistent with old mongo and could be problematic for any integrations that depend on the Discussion ID.
1. Create a course while split is set as the default modulestore (Set `DEFAULT_STORE_FOR_NEW_COURSE` to `split`)
2. In the new course, create a Section, Subsection, and Unit
3. In the new Unit, add a Discussion block. Do not "Edit" the block.
4. Refresh the Unit page in studio and notice the Discussion ID changes every time.