Unable to select a new message in the queue for processing
Get user to confirm they are not currently processing any inbound messages - you will need to confirm that their limit hasn’t been reached for concurrent message processing. Get user to Refresh their screen (F5) and then confirm if the following text ‘You have # open messages’ appears at the top left hand side of their screen;
If yes then they need to click on this underlined text and you need to get them to tell you how many messages of each channel type they have assigned to them and compare these with the values that appear against their user record / the site settings for concurrent message processing.