Showcase module not working in J!3.5

I've updated my Joomla installation to 3.50. The showcase module was working fine until I updated from 5.0.32 to 5.0.34. It won't save a different layout. The database shows... "layout":"_:default" as the setting. Is it supposed to have _: before the word "default"?

Also, the module menu tabs are missing - Module, Menu Assignment, Module Permissions, Post Cover, Advanced