preserve timestamp option ignored when syncing via script

I have trouble getting the preserve timestamp option disabled when using a scripted batch job to synchronize a remote folder. I have tried configuring the option from the gui, directly to the windows register and with a .ini file, but nothing seems to help. I get no errors when transferring files from the gui, but the script halts with the "Upload of file <filename> was successful, but error occurred while setting the permissions and/or timestamp" error regardless of settings.

Am I missing something?

"Preserve timestamp" is always enabled for synchronisation (both via scripting and GUI). AFAIK the synchronisation would not make sense otherwise.