The conversations screen, NLU inbox, and TTYB have in common that they all require a successful path from Rasa OSS through event broker through event service through DB to display conversations/messages. A channel like Slack does not require this connnection, since the response comes directly from the Rasa OSS instance - if there is no successful connection to the DB, the conversation will not be saved, but the end user will still be able to talk to the bot. See the architecture diagram. I marked it up, the red paths are the ones that might be broken:
When it comes to conversations not making their way to the NLU inbox/conversations screen, the most likely culprit is the event broker - if you’re using a standard set up, that’s RabbitMQ. Check that Rabbit isn’t showing errors, restarting, or running out of memory. I’ve seen too low resources for Rabbit cause problems for a few people recently. The next thing to check is the connection to the DB. Does the event service logs (which are Rasa X logs) indicate successful connection to the DB on startup? Can you fetch conversations from the DB using the API?