DT 3.2.1@LinuxMint19.3
When using “file manager” lighttable mode, I can set and see star ratings. Let’s say I gave these bad quality but funny shots 2 stars:
I can click (or use key binding) to change rating but it’s still invisible in culling mode. When I revert to “file manager” mode, I see changed ratings:
You can make the star rating visible choosing an approriate overlay mode. Click on the star symbol (see screenshot below) and select the mode fitting your needs from the menu (e.g. “overlays on mouse hover”). Now hovering the mouse over the image shows a box including the rating.
By default, on culling mode, block overlays with infos and stars is visible only when hovering the image with mouse cursor. On your screen capture, image is not hovered (no white border around the image).