Issue Debugging Record Trigger flow on opportunity for send slack message action

Hi All, 

I am simply trying to send a slack channel message whenever an opportunity moves to closed won stage.  

I have an opportunity record trigger asycn flow that simply runs down the 'run async' path and has a decision check on the opportunity stage. If closed won, it runs down to Send Slack Message action and I have populated the required fields, slack app, slack workspace, executive action as, slack conversation id, and the slack message. 

However, during debug in my developer sandbox, I keep getting the error message:  

" 

We couldn't run action

Hide Error

Info

Error

An error occurred. Try again, or contact Salesforce Customer Support and provide this error ID: 1299900440-35892 (820288246)

Inputs

slackAppIdForToken = A03269G3DNE

slackWorkspaceIdForToken = T0AUVR7GZ62

userIdForToken = null

slackConversationId = C0AUUNER0PP

slackBotName = null

slackMessage = {!tt_SlackClosedWonNotification} (Hello team, A new opportunity has been marked Closed Won. Here are the details: Opportunity: Test Contract Type Account: 001WG00001AjV6DYAV Owner: Amount: Type: New Business)

viewApiName = null

recordId = {!$Record.Id} (006WG00000sl8HZYAY)

slackMessageTimestamp = null 

" 

Am I doing something wrong? The details appear to be grabbing the correct values from my test opportunity? Perhaps my slack conversation id is incorrect? 

Thanks in advance.  

-Roman