Slack message never updated

[Mongey]

When a deployment changes, the slack message isn't getting updated.

{"level":"debug","ts":"1555037765.003300","id":"1c28efbe-a585-8293-c887-3090cd02a22e","time":"2019-04-12T02:56:05.633264596Z","message":"adding new entry into notifier state tracking"}
{"level":"info","channel":"monitoring","channel-id":"C0PB0KCJY","time":"2019-04-12T02:56:05.633310764Z","message":"successfully sent new Slack notification"}
{"level":"debug","time":"2019-04-12T02:56:23.122385767Z","message":"deployments index has changed"}
{"level":"info","job":"nginx","time":"2019-04-12T02:56:23.122415727Z","message":"job deployment index has changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122502500Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122510966Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122516675Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122521775Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122526552Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122531275Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122536018Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122540788Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122545551Z","message":"job deployment index has not changed"}
{"level":"debug","job":"nginx","time":"2019-04-12T02:56:23.122550310Z","message":"job deployment index has not changed"}
{"level":"error","error":"channel_not_found","channel":"monitoring","txt":"","channel-id":"","time":"2019-04-12T02:56:23.246392723Z","message":"failed to send update Slack notification"}
{"level":"debug","ts":"","id":"1c28efbe-a585-8293-c887-3090cd02a22e","time":"2019-04-12T02:56:23.246494282Z","message":"adding update into notifier state tracking"}
{"level":"info","channel":"monitoring","channel-id":"","time":"2019-04-12T02:56:23.246512445Z","message":"successfully sent new Slack notification"}

The error is "channel_not_found".
It does send the initial message, and then later claims the message was sent successfully, but it doesn't seem to update slack. I added some more information to the logs to try debug, (splitting channel id and channel).