This will be improved in the new release:
https://winscp.net/tracker/1752

The new file is created (uploaded) only after you press Save in the (internal) editor.

I'm unable to create new files on (any) remote server through SFTP. I should note that I can actually create directories and upload existing files, so it's not a matter of permissions on a server. The behavior is that whenever I attempt to create a new file (Right Clicking, or selecting New from the toolbar), I am prompted for a name for the file. After that, the internal editor opens, but no file is ever created. In fact, hitting refresh on the editor just says that the file does not exist. I've attached a log-file where I've connected to a server, first created a folder, then attempted to create a file. Sensitive information replaced with [## ##]. If I may note, it seems like the first mention of 'new-file' is attempting to list it, I couldn't see anywhere it attempted to create it as it did with 'new-folder'.

Using WinSCP 5.15.1 on Windows 10 (64-bit) with either interface style.