“PressApps” menu is available to the role, but it’s not shown by “Admin menu” window, right?
It seems this plugin addes ‘pa_non_existent_capability’ programmatically, on the fly and uses some tricks with it (possibly filters), instead of adding it to the role directly.

You may send a copy of ‘PressApps Knowledge Base’ plugin to support email. I will investigate how to make its menu available for “Admin menu access’ module.