Related situation here but I'm going backwards:
I have an area on my website for clients and I was creating unique directories for each client like:
I created a user aa then remapped the subdir:
from /client/aa to /home/aa/files
I then put the client into its own group as grpaa in case I create more users for each client.
I added my main user to that group as well, so now both users are in the default pgxxxx group and grpaa.
Here's the issue: I can create files in /client/aa with main, chgrp all files to grpaa, and change all permissions (for now) to 770 or even 777. I can shell in as aa and do the same in /home/aa/files which looks like it's a real directory - I didn't create it, the CP created it when I did the mapping. But aa can't see files created by main and main can't see files created by aa.
So now that the mapping is created and all permissions are in place, why can't I see files from both directions?
I hope this helps the OP too...