Simply put: signing out of the app will delete all data, always. The only way to preserve it is to synchronise the data to the server before signing out.
Hi, I am also experiencing the same problem. This behavior is inconsistent with the documentation, which states that items for which the anonymous user does not have access are removed. If all roles, including anonymous have access to the entity then the documentation implies that it will persist. This is the first place I have seen where it is written that "signing out will delete all data, always."