Please doublecheck our troubleshooting guide to make sure you are not hitting one of the known limitations. This one seems particularly relevant: "Arc Resource Bridge provisioning through command line must be performed on a local HCI server PowerShell. It can't be done in a remote PowerShell window from a machine that isn't a host of the Azure Stack HCI cluster. To connect on each node of the Azure Stack HCI cluster, use Remote Desktop Protocol (RDP) connected with a domain user admin of the cluster."
If you are still facing issues, I have reached out so we can work with you directly.
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