botframework-sdk: Can't use prompts in proactive dialog

My use case is this:

1. User A initiates conversation with the bot
2. According to the conversation result, the bot triggers a dialog with user B via bot.beginDialog (proactive).
3. The bot presents user B with a confirmation prompt.
4. User B answers the prompt (“yes”).
5. Bot returns “I didn’t understand” error.

What’s happening is that the answer to the prompt is received in a different dialog than the one triggered in step 2 (the root dialog from the previous conversation). Which is confusing, since the documentation for bot.beginDialogsays:

Proactively starts a new dialog with the user. Any current conversation between the bot and user will be replaced with a new dialog stack.

But it seems that the dialog stack isn’t really replaced, as the incoming message isn’t directed to the input dialog.

I’m using UniversalBot with ChatConnector, Node.js SDK version 3.1.1. I’ve reproduced it on several channels (Slack, Skype, Facebook).

Am I missing something here?