Alias folders appear as generic on re-start (do not retain custom icon)

This is a copy of a post which appeared here last November. I thought I'd solved the problem by using the 'make alias' shortcut (Cmd/L) of a folder and placing the alias on my desktop for easy access. I would then access 'Get Info' on the alias (Cmd/I) and copy and paste the alias's custom icon into itself. But with the latest OS High Sierra, that solution doesn't seem to work (although it may for others).

Disk Utilities' First Aid, doesn't help.

Also, when I recreate an alias on the desktop, the custom icon appears correctly but disappears after restart.

Does anybody have a suggestion as to how to remedy the situation?