Symptoms
Permissions for additional FTP accounts are vanished after checking security with “Check Permissions” option in Plesk, or running permission check through Plesk Reconfigurator.As sequence the following error appears when trying to login using these accounts:
530 User ftp_sub1 cannot log in, home directory inaccessible.
Resolution
To avoid such behavior please download the following files:http://download1.swsoft.com/Plesk/Autoupdate/Windows/8.2.0/123969/gene6provider.dll
http://download1.swsoft.com/Plesk/Autoupdate/Windows/8.2.0/123969/iisftpprovider.dll
and place them to %plesk_bin% folder.