Slack intergrated, but no any messages

Hello there!
Sentry 21.4.0.dev0 on-premise (self-hosted).
Slack is integrated, inside Integtarions → Slack status is “Enabled”
I can create any rules for any project, added Sentry to my channel, but if I will generate test issue inside any project with rules - there is no any messages inside slack.
Why? How I can troubleshoot this problem?
Alert rule is quite simply:

Thank you,
Best regards

And additional info - added email to this rule - it is not working too
added slack-webhook to this rule, and webhook sends slack messages with “Route not found” and generates this issue inside “INTERNAL” (but rule is not for internal)

Nevermind, I’m accidently break sentry and slack integration seems ok. Just Sample Issues did not send anything to the Integration