I installed SQL Server 2017 Express as a named Instance alongside my default instance. After rebooting once - both were showing but the I could not connect to SQL Server Express remotely. I then followed the instructions to enable IP on SQL Express using configuration manager and rebooted. Now I can connect remotely but my default instance is showing NO databases!
Also in configuration manager, SQL Server Services does not show any of my instances so that I can check they are running (this was the care even prior to enabling the IP address on the protocol, and when I knew it definitely was running as I could connect to it)
-- Update: I discovered if I launch SQL Server Configuration Manager 2016 rather than "SQL Server Configuration Manager" I can see all my servers. SQL Server 2016 appears to be running as is SQL Server Express. There is also a "MSSQLServer" that is stopped - think this may be SQL Server 2012. Not sure at this stage which one had the databases.