This is a known behavior and usually comes down to how the slot output variables are being referenced and stored.

A few things to check that typically resolve the ${startTime} showing as null:

1. Verify the output variable mapping The Fetch Appointment Slot node does not automatically expose ${startTime} unless it is explicitly saved.

• In the Fetch Appointment Slot node, make sure the slot start time is mapped to a flow variable (for example: slotStartTime)
• Use that mapped variable in your prompt instead of ${startTime} (for example: ${slotStartTime})

2. Confirm the node actually returns slots If no slots are available at runtime, the variables will return null even if everything is configured correctly.

• Make sure the assigned agent is available during the configured slot hours
• Ensure the queue assignment has at least one eligible agent at that time
• Test by restricting the time window to a short range to confirm slots are being generated

3. Use the correct playback variable The Fetch Appointment Slot node typically returns an array of slots.

• If multiple slots are returned, you may need to reference the first item (for example: slots[0].startTime)
• Playing back ${startTime} alone will return null if it’s not a top‑level variable

4. Time zone consistency You’ve already set IST in both Slot Availability Manager and IVR, which is correct. Still, confirm:

• The IVR flow level time zone matches IST
• No downstream nodes are overriding the time zone

5. Test with a Set Variable node As a quick validation step:

• Add a Set Variable node right after Fetch Appointment Slot
• Assign the returned start time to a test variable and log or play it back This helps confirm whether the value is being returned but not referenced correctly.

In most cases, this issue is caused by either:

• Not mapping the slot start time to a variable, or
• Referencing ${startTime} instead of the actual returned slot object or mapped variable

If the issue persists after validating these points, enabling IVR execution logs and checking the Fetch Appointment Slot response payload will help pinpoint whether slots are being generated at runtime.

Hope this helps!