"page Masthead" Billboard Doesn't Work On Client Galleries?

I want client galleries to start with a full screen image. The "page masthead" doesn't seem to work. The documentation says it'll pull the first photo, or the cover photo, but in practice it just spins and spins like it's trying to load a photo but there's no photo to load.

I tried to create a custom billboard, but it seems that would require a unique custom billboard for every single client gallery.

How do I do this?

The "page masthead" you need to select in the section / category settings to automatically add to the gallery. Selecting it for the gallery itself won't work.

Edit the section your galleries are in and scroll down on the right click Design Options then check the box next to  "Display a masthead (1 billboard slide) of the first photo or cover photo on pages displayed in this section. You can edit the layout of it in the Site Design -> Billboards section."

Okay, this works. Can these be styled? Like, can the background image get a color overlay? Can the text simply be centered vertically and horizontally? Can relevant text be added, for example the session date or location?

There aren't any styling options. It simply displays the photo.

There is a gallery exclusive mode that adds the full screen  photo with the gallery name.

Manual. 

Example.