Create Chat/Send Text to SMS Target

[JUSTINMKAUFMAN]

First of all, I am able to send SMS from the Messages app on the Mac where the server is running.

The issue I am seeing is:
When sending the first message to a new SMS target (i.e. one with no iMessage availability)...
it attempts to send it via iMessage...
immediately returns a success response to the client...
but actually fails to deliver the message...
and never emits a message send error webhook or anything.

If I go into the Messages app, click the red ! and click 'Retry as Text Message', it works and then all subsequent send requests to that contact work perfectly via SMS.

Normally I call Create Chat when sending the initial message to a new contact (this works for iMessage at least), but I have also tried skipping this and just calling the Send Text method for SMS targets (manually constructing the chatGuid as SMS;-;+{phone}.

Has anyone else experienced and/or solved this?