Why it occurs
This happens when the Select senders for each queue option is enabled for a queue, but no sender has been assigned to that specific queue. Without a designated sender, agents won’t be able to send replies to conversations routed to that queue.
For more details, refer to the Senders configuration documentation.
Steps to resolve the issue
1. Go to the queue settings
– Go to Conversations → Settings → Queues.
– Select the name of the affected queue, such as Default queue.

2. Assign a sender to the queue
– Scroll to the Assigned Senders section.
– Click Add Sender.
– Select the appropriate sender based on the channel, such as Live Chat or WhatsApp.
– Click Add.

3. Select the sender in the conversation
– Return to the affected conversation.
– Use the From field to select the newly assigned sender.

4. Confirm the agent can reply
The Reply button should now be active, and the agent will be able to send messages.