MPB shows custom sidebar icons but Mac mini not

I have Synology drive installed in both my two Macs, one Mac mini M2 Pro and one MacBook Pro M1 Pro. In my MacBook Pro if I drop the Synology Drive synchronised folders, I see its own custom icon:

However, in my Mac mini they are shown as normal default icons:

In the capture you can see that the folder has the customised icon, and is shown as customised inside Finder but not in the sidebar. I've tried the typical stuff, like remove, add, restart... with no success.

Any idea why this happens? Thanks in advance