Web service ticket creation fails to include CustomerID or Reply options

[z1001z]

Setup: otrs 6.0.16, Centos 7, python-otrs, using, GenericTicketConnectorSOAP.
Python script makes very simple call to TicketCreate following the unit test in the docs.
Ticket and Article is created OK, in the correct queue and auto-responder goes out correctly. However when the ticket is opened by agent, there is no "Reply" option and none of the queue's normal templates are available.
I notice unlike normal incoming email tickets, there is no CustomerID shown. Any clue as to what may be missing? This is my first ever attempt to create a ticket by a remote script, so any more developed example would also be helpful.

[crythias]

However when the ticket is opened by agent, there is no "Reply" option and none of the queue's normal templates are available.

Reply works if ...

Ticket is unlocked or
Ticket is locked and current agent is owner or responsible
and
Article is "from" customer. Should have customer_id attached. Push it through web service.

Otherwise New outbound email or forward.

[z1001z]

Thank you for explaining the reply rules.