I don't have any project using files opened via FTP (FTP based project). According to the power tip
Configure FTP Backup and the UltraEdit help for
Local Copy Directory this directory is a backup from what is on the server. It is just a local backup for the files on the server. It looks like it is not designed that you open files from this local backup directory and on save UltraEdit automatically logs in on the server and uploads the file. You have to manually upload it when modifying local files. But if you open a file via FTP and save it, UltraEdit creates first a local backup and then uploads the file.
What you want is explained in the power tip
Link remote directories to local directories. But as described in step 4, you have to upload the modified files manually. Of course you can upload whole folders and folder structures. I don't know if UltraEdit determines which file was modified in a directory and uploads then only the modified files in the directory or all files. In the FTP log you should see if UE just uploads all files or runs a synchronize.
If you make changes in many local files at once, for example with a Replace in Files operation, it would be better to use UltraCompare Professional or a special FTP client like Total Commander or WS FTP to synchronize the local files with the files on the server if UltraEdit uploads always all files instead of using a synchronization mechanism.
Please note, I don't have experience with working with files via FTP in UltraEdit. Maybe somebody else has more knowledge than I.
You can also contact the IDM support per email and ask for help. With buying the license you paid also for the support by email. That's one of the main differences between freeware/open source applications and shareware/licensed applications - individual support by the producer of the application is often implemented in the price.