This is engine_main.log though:

Loading mods in 'mods'
Connecting to storage
Storage connection lost { Error: connect ECONNREFUSED 127.0.0.1:21027
at Object.exports._errnoException (util.js:1026:11)
at exports._exceptionWithHostPort (util.js:1049:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1081:14)
code: 'ECONNREFUSED',
errno: 'ECONNREFUSED',
syscall: 'connect',
address: '127.0.0.1',
port: 21027 }
Connecting to storage
Storage connection lost { Error: connect ECONNREFUSED 127.0.0.1:21027
at Object.exports._errnoException (util.js:1026:11)
at exports._exceptionWithHostPort (util.js:1049:20)
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1081:14)
code: 'ECONNREFUSED',
errno: 'ECONNREFUSED',
syscall: 'connect',
address: '127.0.0.1',
port: 21027 }
Connecting to storage

Thanks Artem - the server seems to think it's getting connections:

Loading mods in 'mods'
Starting storage server
Storage listening on 21027
[127.0.0.1:50064] Incoming connection
[127.0.0.1:50065] Incoming connection
[127.0.0.1:50066] Incoming connection
[127.0.0.1:50067] Incoming connection
[127.0.0.1:50068] Incoming connection
[127.0.0.1:50072] Incoming connection

(that's it!)

No game ticks are occurring on my local server; i.e., I can start the server, connect to it with the client, and place a Spawn, but nothing happens; my scripts are not run, my Safe Mode timer does not decrement.

Numerous errors are shown in the server console, unfortunately it doesn't seem possible to copy & paste from these (are these available as files anywhere?)

These include: 

- "Storage connection lost { Error: connect ECONNREFUSED 127.0.0.1:21027...

- TypeError: Cannot read property 'clear' of undefined at Array.sendNotifications...

- Unhandled rejection: Error: Can't set headers after they are sent

Running under Steam client on Mac OSX 10.12.1

Same problem for me, and I run my own email server so it's not something that's happening / changed on my side; my settings in the game are correct as below.