I copied all files through smbclient to the destination. As this did not preserve the mod-time I decided to use rclone to correct this. If the destination does not contain the files the mod-time of all files is set correct, but if they already exist, their mod-time is not updated altough I do not set --size-only or --no-update-modtime?!
What is your rclone version (output from rclone version)
go version: go1.13.7
Which OS you are using and how many bits (eg Windows 7, 64 bit)
Which cloud storage system are you using? (eg Google Drive)
The command you were trying to run (eg rclone copy /tmp remote:tmp)
Oh I see, you are copying from FTP to local. Rclone will preseve times that are set on the FTP server when it reads stuff to local disk. However it can't set times on the FTP server when copying the other way - there isn't a standard FTP command to do that though there are quite a few alternatives rclone could use if it was important!