That's weird - I get the exact opposite behavior.
View Extras shows a preview pane for me (just like in the past), but when I launch Rich Data, it creates a playlist - no preview pane. Do you have all the files inside a zip file (and do a full restart of MC as well)?
When I launch Rich Data it creates a Playlist of the Rich Data images in my zip file, in a Standard View "Rich Data" Tab. Hover over a Playlist image to bring up a small "+" sign in upper left corner of the image. Click the "+", or double click a Playlist image. It turns into a Standard View with the a lower left corner menu (see attachment). In this menu, be sure "Hide Files" is unchecked. Then the Standard View has a large selected image with the smaller playlist images visible in the right sidebar pane. (At this point, visibility of this right sidebar pane is also controllable with the small vertical splitter arrows, as usual.) If I switch to Cover View I also see the sidebar with image playlist. Now hover over a playlist image in the sidebar to bring up a small "-" sign. Click "-" and it returns to the initial Playlist in a Standard View Tab.
Note: If I click the Play Tab in Rich Data's initial Playlist, it jumps straight into Display View and I do
not see the attached menu or the sidebar playlist. Probably this is your experience. In any case, Rich Data deserves a Wiki page, of the same high quality as the Playing Now Popup wiki.
For whatever reason, I have never seen the Playlist or Playlist Sidebar after RMB on a View Extras menu item and have never seen a menu equivalent to the attachment. It goes straight into Display View without sidebar. Am I missing something? Hence my interest in having View Extras and Rich Data use the same type of display interface, even as Rich Data evolves. Seems like low-hanging fruit to me.
However, consider adding a screen option/shortcut to toggle off/on the sidebar preview strip, displaying as a slideshow only. There are likely times when users may prefer not to see the sidebar.
Whoops... Three ways to hide the sidebar are described above! Still another way is to tap the space bar, which enters Display View. In Display View with hidden sidebar, navigate through images by double tapping the space bar,
right/left arrows,
Pg Dn/Pg Up keys, or play the slideshow. In Standard View with sidebar images visible, navigate through images with
down/up arrows,
Pg Dn/Pg Up, or just click a sidebar image.
5/6/2025 Minor edits of 3rd paragraph. Add quote.
Win11 64-bit | MC 34.0.23 | Note: Some transition details between views seem to have changed from MC 34.0.23 to 34.0.24 (beta).