filesystem – How can I solve the “Fetching…” issue when assigning users or groups permissions to folders or apps?

In Sequoia 15.1 (but looks an old known issue). Using the GUI, I created a group to bind it to a folder and an application. On both, this happens:

I searched the web but some solutions look very risky as they issue long command line strings in a recursive manner applied to the filesystem.

If solution using this way is far from complicated, how would you, using command line (chown, chmod,chgrp?):

1. Bind (append) a group to a folder or app without overwriting current users/groups.
2. Touch/change just the group/user permissions on that folder or app (leaving alone other users/groups on same app/folder).