FTP Error 530 when using FTP User Isolation on IIS 8

I'm setting up an FTP server on IIS 8 running on a Windows Server 2012 R2 Essentials box. The server is configured to be the physical directory D:\ (the whole drive). I have 3 users: let's say user1, user2, and user3, all of which are in an ftp_users group. I added a read & write allow rule for this group only. Up until this point, everything works fine, but all users have access to the whole directory.

I created 3 virtual directories under D:\LocalUser for each of the users (D:\LocalUser\User1, etc) with physical paths of D:\ServerFolders\IIS\Sites\Site[1/2/3]. I configured FTP user isolation to isolate users to their user name directory (disable global virtual directories). Once I do this, users can no longer connect to the FTP server, with the following logs from FileZilla:

Status: Connecting to <ip address>:21...
Status: Connection established, waiting for welcome message...
Status: Insecure server, it does not support FTP over TLS.
Command:    USER user1
Response:   331 Password required
Command:    PASS ************
Response:   530 User cannot log in, home directory inaccessible.
Error:  Critical error: Could not connect to server

As a note, I'm not using SSL at the moment.

Thanks in advance for any assistance!