I have fixed the props atlas. Regarding the PCs, the original positioning was intentional, but following your feedback, I centered them better within the tile. Just a heads-up: to make some props fit the grid better, I had to resize them slightly, so you might notice some minor differences compared to the original standalone assets.
Since the rest of the atlases seem to be working fine, I will proceed with creating the atlases for the other backgrounds and props over the next few hours.
Let me know if they work well for your project so I can permanently include them in the .zip files. Talk soon and thanks!