I've just checked the plugin and see that the TGM Plugin Activation class doesn't show the notice for ones who have dismissed it. Can you tell the clients to click the dismiss link? It works per user, so if you have dismissed it, your client might still see it.
The problem is that even after clicking dismiss, it keeps coming back.
Same happens with an alert about an update available for Meta Box AIO.
It keeps telling me that an update is available, even after I have manually updated that plugin to the latest version 1.5.9, it says that 1.5.8 is installed.
Where can I send you user/password to the site, so you can investigate?
I also found a but related to Astra "UABB Info Box" module and Meta Box, already tested by the Beaver Team.