FTP delete directory fails when it contains a hidden file

[volcs0]

Title says it all.
I'm using FTP for synchronization between a local directory and my unRAID server share (it's so much faster than SMB).
But every time FreeFileSync tries to delete a directory, it throws an error.
When I went to inspect the folders, it was not a permissions problem.
However, the folders it could not delete have hidden files in them.
When I delete the hidden files, then the remove directory works.

Any way to work around this?

Thanks.

[Zenju]

What type of hidden files are these that FFS cannot see them?

[volcs0]

They are hidden files with the same names as some of the files in the folder.
e.g.,

-rw-rw-rw- 1 nobody users 4096 Jul 21 2019 ._09\ Tracy.flac
-rw-rw-rw- 1 nobody users 4096 Jul 21 2019 ._18\ Chasing\ John\ Doe.flac
-rw-rw-rw- 1 nobody users 4096 Jul 21 2019 ._19\ The\ Apartment.flac
-rw-rw-rw- 1 nobody users 4096 Jul 21 2019 ._24\ Wearing\ the\ Wire.flac
-rw-rw-rw- 1 nobody users 4096 Jul 21 2019 ._25\ The\ Desert.flac
-rw-rw-rw- 1 nobody users 4096 Jul 21 2019 ._26\ Envy\ and\ Wrath.flac

Any thoughts?

If I delete these manually, then there is no error on director deletion.

Thanks.

[Zenju]

The FTP server is probably hiding them directly from the directory listings (instead of returning them and letting the client app hide them if it wants to). Are other FTP clients able to list these files?