-criteria=checksum fails second authentication

Hello, I am at my wits end with a script supposed to syncrhonize a local folder with a remote folder, this works:

synchronize local -delete -mirror -rawtransfersettings[1] ExcludeHiddenFiles=1 H:\ /service/software/SSD

But if I add -criteria=checksum:

synchronize local -delete -mirror -criteria=checksum -rawtransfersettings[1] ExcludeHiddenFiles=1 H:\ /service/software/SSD

This causes the second part of the authentication to fail, reason given is that it cannot read the private key.

Script: Credentials were not specified.
< 2026-04-25 14:26:14.752 Authentication log (see session log for details):
< 2026-04-25 14:26:14.752 Unable to use key file "key.ppk" (unable to open file)
< 2026-04-25 14:26:14.752 Using username "key".
< 2026-04-25 14:26:14.752
< 2026-04-25 14:26:14.752 Authentication failed.
. 2026-04-25 14:26:14.752 Script: Failed

If I just remove the -criteria=checksum switch from the command, everything is fine.

Any idea?

Thanks