Custom Webhook works with "Run once" but not "Immediately as data arrives"

Questions
1

:bullseye: What is your goal?

Input received by webhook (when using Run once):

  • Timestamp: 1763762341098
  • Type: tool-calls
  • message.toolCalls[1].function.name: get_available_times
  • message.toolCalls[1].function.arguments.service_type: home_inspection

HTTP module output (Status 200 from Calendly):

  • Status code: 200
  • data.collection: (empty array)

VAPI Respond module input:

  • Tool Call ID: call_K9FcHgk2J8AM8N51Crta5VTk
  • Result:

Everything works with “Run once” but nothing triggers with “Immediately as data arrives” enabled, even though VAPI shows “Completed successfully” with 200 response.

:thinking: What is the problem & what have you tried?

  • Enabled “Immediately as data arrives” and saved scenario
  • Toggled setting off and on multiple times
  • Saved scenario with floppy disk icon after each change
  • Verified scenario is ON (blue toggle)
  • Tested webhook URL directly in browser - returns “Accepted”
  • Created new webhook and replaced old one
  • Confirmed external service (VAPI) receives 200 response when calling webhook
  • Verified plan allows 2 active scenarios and both slots are used

:clipboard: Error messages or input/output bundles

Input received by webhook (when using Run once):

  • Timestamp: 1763762341098
  • Type: tool-calls
  • message.toolCalls[1].function.name: get_available_times
  • message.toolCalls[1].function.arguments.service_type: home_inspection

HTTP module output (Status 200 from Calendly):

  • Status code: 200
  • data.collection: (empty array)

VAPI Respond module input:

  • Tool Call ID: call_K9FcHgk2J8AM8N51Crta5VTk
  • Result:

Everything works with “Run once” but nothing triggers with “Immediately as data arrives” enabled, even though VAPI shows “Completed successfully” with 200 response.

3

Welcome to the Make community!

The scenario is probably still running in the background.

To see if it actually ran, go to the Scenario “History” tab.
Screenshot 2025-11-24 162155

Hope this helps! If you are still having trouble, please provide more details.

— @samliew
P.S.: investing some effort into the tutorials in the Make Academy will save you lots of time and frustration using Make!