As a workaround to https://answers.splunk.com/answers/761034/slack-alert-not-sending.html, I've used a single space " " as an specific alert parameter to fix the issue. Therefore the parameter in savedsearches looks like
However upon reboot, that space gets wiped (which disables the Slack alert per 761034).
My question is...
How do you specify whitespace in savedsearches so it doesn't get wiped on reboot?
This is a terribly inelegant answer and I truly hope someone posts a better answer. But it works. Must have the blank line after. Not sure how you do this is you want a specific whitespace character.
action.slack.param.message = \
alert.digest_mode = 0