Why am I getting "could not find file" errors when using Remove-Item in PowerShell?

Question

I am running the following in my PowerShell script:

Get-ChildItem -LiteralPath $source -Force -Recurse -Directory | ForEach-Object {
    Write-Output "Removing files in folder $($_.FullName)"
    Get-ChildItem -LiteralPath $_.FullName -Force -File | ForEach-Object {
        Write-Output "Removing file $($_.FullName)"
        Remove-Item -LiteralPath $_.FullName -Force -ErrorAction Stop
    }
}

This is a PowerShell script running inside an Azure Automation Account, to be able to cleanup folders on a Panzura File Server when they are no longer needed.

This is failing and giving me logs like:

Removing files in folder C:\Folder\SubFolder
Removing files in folder C:\Folder\SubFolder\SubSubFolder
Removing files in folder C:\Folder\SubFolder\SubSubSubFolder
Removing file C:\Folder\SubFolder\SubSubSubFolder\SomeFile.tmp

Could not find file 'C:\Folder\SubFolder\SubSubSubFolder\SomeFile.tmp'

Even though the file was found inside a sub-folder when using the folder's LiteralPath in Get-ChildItem and then FullName when using Remove-Item.

It's like these files are locked somehow and cannot be deleted and so these errors are thrown.

How can I avoid this? Is there any way to forcefully delete these "locked" files, more than using '-Force' in my command?

Thanks!