Content Apps that share workspaces and use a content connector do not save newly created content in the location configured within the rootPath property.

Can confirm on 6.1.2 by creating 2 content apps that share the same workspace then having each one have different rootPaths. When you create new content, you will see that they do not appear within the content app, but they do appear in the JCR saved to the root of the workspace instead of the configured rootPath. If you move the new content node from within the JCR into the proper rootPath node manually, then the newly created content appears in its respective content app.

See linked support ticket for examples and screenshots.

This appears to be due to missing/incomplete content connector configuration within the detailTemplate.yaml file Magnolia uses to construct content apps from the content type. If we override the content connector's rootPath manually then it works.