If you work on custom DSC resources then debug mode is very handy for you because you may need to re-import your updated DSC resource again and again. Without re-import (force import) the DSC uses cache.

How to set DebugMode:

• None
  • Signifies that DebugMode is False and not applicable.
• ForceModuleImport
  • Enforce the resource module to be reloaded instead of using the cache. This is similar to “true” value in previous versions.
• ResourceScriptBrealAll
  • Helps in debugging DSC resources when Local configuration manager tries to execute their functions. More on it in subsequent blog posts!
• All
  • Signifies that debugging as well as reloading of modules are both enabled.

[DSCLocalConfigurationManager()]
Configuration LCMDebugMode {
    Node localhost {
        Settings {
            ConfigurationMode    = 'ApplyOnly'
            RefreshMode          = 'Push'
            Debugmode            = 'ForceModuleImport'
        }
    }
}

LCMDebugMode -OutputPath $directoryPath
Set-DscLocalConfigurationManager -Path $directoryPath -Verbose
Get-DscLocalConfigurationManager

The second option to mitigate cache is to restart service but this is not recommended procedure:

Restart-Service -Name winmgmt -Force -Verbose