Here's the ProFTPd log that shows the issue:



It seems PHPEd issues MDTM to change file mtime, which is wrong, MDTM is defined for retrieval only and MFMT must be used instead to modify.
This obviously causes a multitude of issues with smart sync as remote file mtimes are not updated properly.
The syntax seems to be correct for MFMT as well, so probably just a typo in the command name?

PHPEd version: 23.0 (23016)

No, it’s not a typo. If the server advertises support for MFMT, PhpED uses it. Otherwise, it checks whether MDTM is advertised with different combinations of date/time and time zone info. If none of these options is supported, it falls back to the plain MDTM you see in the log.
For instance, Pure-FTPd advertises support for MFMT and works without any issues. FTP Voyager support MDTM.

Fixing the command may not help if your server does not support it.
Which server software and version are you using? I can check what it supports and what it advertises in the FTP protocol.

Hello Dmitri,
Thanks for the explanation, I will check the FTP server then as then it is a server side bug then.

Please close the topic.

P.S.

Yes indeed, was required for ProFTPd to announce MFMT support.

Just as a side thing, are other FTP features that are required or may be handy to optimize the sync listed somewhere?

If MFMT works, that’s all you need for reliable sync over FTP.