iOS: Missing reply textbox on messaging screen when launched

Our app contains a button that launches zendesk messaging on our login page (for eg if user has forgotten their pin).  The problem is as follows:

1. User launches the zendesk messaging view from our login page, and starts a conversation (first with bot then with live agent).  Reply textbox appears ok and user can interact with first the bot, then a live agent.
2. User closes the app
3. User restarts the app, then on the login page again, reopens the messaging window to show the conversation restored in its previous state
4. At this point the reply text box is not visible, and user cannot create a new message

Ive also observed an error message in logging:

[EFFECT_PROCESSOR] 14:00:01.998 DEB 'networkConnectionStatusUpdate(ZendeskSDKConversationKit.ConnectionStatus) cannot be performed on integrationAccess(integrationProcessor: ZendeskSDKConversationKit.IntegrationProcessor)'

Ive tried allsorts of different ways of presenting the view: Im sure its not to do with the textbox being hidden at the bottom of the page, for eg.  Ive checked and the view is full screen correctly.  Seems like the page doesnt fully initialise and add the reply textbox for some reason.