Directories are missing when using DNS alias for FTP/FTPS connection

Using FTP server DNS alias for FTP/FTPS connection in PSPad (5.0.6) fails to show directories on FTP server.
FTP/FTPS connection using FTP server hostname is able to show directories.
Is it possible to fix this issue as we would prefer using DNS alias?
It is also working correctly in other FTP clients (TC, FileZilla, WinSCP).
Our FTP server is running on IIS 10 (Windows Server 2019).
Thank you for any advice.