The documentation implies that data is preserved across user sessions, which is a useful feature, but currently in Mendix 10.18.0 logging out does not preserve data even if the anonymous user has access to the entity.
I went so far as to add a nanoservice that accesses the entity from the login page to try to preserve the Entities, unfortunately the local device database is built from scratch and wipes out Nothing-preserve data Entities.
See this discussion for additional context: https://community.mendix.com/link/space/mobile/questions/140287