Set Participant Data action not persisting custom variables across IVR nodes

Architect & Flows
1

We’re hitting a weird edge case with the Set Participant Data action in our CXone Architect flow. The goal is simple: capture a value from a DTMF input, store it in a custom variable, and use it later for routing logic.

The flow looks like this:

  1. Gather Input action captures digits.
  2. Set Participant Data action maps the result to customVars.customerPref.
  3. IF node checks customVars.customerPref == '1'.

The problem is step 3 always evaluates to false, even though the debug log shows the assignment happened. Here’s the JSON payload we’re seeing in the trace for the Set Participant Data action:

{
 "action": "set_participant_data",
 "data": {
 "customVars": {
 "customerPref": "1"
 }
 }
}

I’ve tried using the REST API directly to verify the variable is set. I attempted to update the participant data directly via the API, but the standard endpoints for managing conversation participants don’t seem to expose a direct way to patch custom variables in the same way the flow action does. When I check the interaction state via the available conversation endpoints, customVars appears empty or undefined in the immediate response.

Wait, that’s not quite right. The variable seems to appear, but only if I wait 200ms. In the flow, the IF node hits immediately after the Set action. Is there a sync delay?

I’ve added a Delay action of 1 second right after the Set action. Still fails. The IF node debug log shows customVars.customerPref is undefined.

We’re using CXone Studio v2. The variable scope is set to interaction. I’ve checked the naming convention-no spaces, no special chars. Just customerPref.

Is the Set Participant Data action async? Or am I missing a specific header in the API call that triggers the persistence? The docs say it’s synchronous, but the behavior suggests otherwise. We’re in America/Chicago, so timezone isn’t the issue here.

Any ideas? We’re stuck on this for two days. The flow just drops to the default branch every time. No errors, just silent failure. Feels like a bug, but I might be doing something dumb. Checked the SDK docs. Nothing mentions a delay.

One more thing: if I hardcode the value in the IF node, it works. So the logic is fine. It’s just the variable passing that’s broken. Or maybe I’m not using the right key? The API docs show customVars as the root, but maybe it needs data.customVars? Tried that. Same result.

Running out of options. Can’t find a working example of this pattern in the community. Just seeing people use ASSIGN actions in Studio, but we need this in Architect for the IVR.

What am I missing?