don´t know if this helps, but spent now hours in the troubleshooting why my asim dns dcr rule wasn´t collecting logs and saw, that the extention didn´t got installed on my machines.
the way how i installed it was via powershell:
Install-module Az.ConnectedMachine
Import-module Az.ConnectedMachine
$extPublisher = "Microsoft.Sentinel.AzureMonitorAgentExtensions"
$extName = "MicrosoftDnsAgent"
new-azconnectedMachineExtension -ResourceGroupName '<RGName>' -Location 'westeurope' -MachineName '<ARCMaschineName>' -Name $extName -Publisher $extPublisher -ExtensionType $extName