There may be two issues at play here (and I suspect it is the first): Changes that Microsoft has made to security means that it is no longer possible to access Nucleus or ROCK folders. Then the Group Policy Editor of Windows can be used to work around this. Windows File Explorer has a habit of not finding non-Windows devices in your network until it’s told to do so. So typing \rock\ in the address field (note: NOT the Search field) of File Explorer will kick Windows into displaying it again. …
If you're using Nucleus One. Thus you must type \\nucleusone\
into File Explorer.