Thank you very much for your help!
I already checked the eCommerce Categories section — since this is a brand new installation, it was empty, so I created new categories with images (e.g., Sofas, Tables, Lamps) and tried inserting the Categories Showcase block again afterward. Unfortunately, the images still don’t change.
I also looked through the other modules (Inventory, Sales, Website, etc.) to see if the sample images are stored elsewhere, but I couldn’t find them.
It feels like there’s a small trick or missing link somewhere, because I don’t think Odoo would release a block that can’t have its content managed.
The same issue also appears in the other catalog block — the Banner Catalog block with the title “Explore our new collection” — it uses the same default images (Sofa, Desk, Drawer) that can’t be replaced.
I’ve tested this across several brand-new installations and got the same result every time.
If you have a moment, could you please try it on your end too? It really looks like a stunning new feature — if only we could make it work!