For case-sensitive file-systems having using this feature can introduce a lot of headaches.
While there are a few rare situations where this type of feature can be useful we've decided that for now we will not expand it to folders, of course if there is enough interest for such feature we will add it.
Another thing to consider, say you queue a folder named "HELLO WORLD" to upload to a case-insensitive FTP server with a folder already named "HeLLo WoRlD", since the folder already exists the case of the folder name will not change. Now say you want to transfer the "HeLLo WoRlD" from the case-insensitive FTP server using a site to site transfer to another FTP server which is case-sensitive and this server already has a folder named "HELLO WORLD" what you end up with is two folders "HeLLo WoRlD" the existing folder and a new folder "HELLO WORLD".
If you want to rename a batch of files/folders from their current case to say lowercase I do offer you a solution.
Create a new custom command (Commands > Edit Commands > New Command)
Code:
{
RNFR %f
RNTO $LowerCase(%f)
}
Select the desired files/folders from the file listing and then run the command from the command menu.
This command macro isn't recursive and it may or may not work with all FTP servers.