I’m having a similar problem trying to copy files into a WSL2 location. This is generally accessible from \\wsl$\<distro> and I even have a drive mapped to the location. I can navigate to the location using Windows Explorer with ease, and even manually create files. However, I haven’t been able to figure out how to use deployment tasks to copy by certs into the WSL2 location. Everything I’ve tried (mapped drive letter, UNC path, etc.) fails with no information about why.
I’ve never tried that with WSL but the Certify background service runs at Local System, so the wsl share path would need to be accessible to that process. Try using psexec to get a command line as System (psexec -i -s cmd.exe) then see if you can still copy files to the wsl share path
Note that if you can enable and configure SSH on wsl you should be able to use that instead of the machine share.
I should have mentioned that I also tried with a “Local as another user” option (or whatever that’s called) and it didn’t help.
I think the problem may be related to the different account the service runs as, so it doesn’t have access to the virtual machine related resource/layer (which is wrapped in an app resource) that you would normally have as the logged in user. SSH will work though (this is also closer to how it would be done if deploying from windows to any other linux host).