Hi @DavidTurner ,
Can i try @Christian_Dahlqvist solutions , will it solve my issue,
this solutions
Change the type of storage you are using for the cluster. Based on naming it seems you might be using Azure Files, which I believe is not suitable for Elasticsearch. If this is the case I would recommend switching to Azure Managed Disk.
As the index has been corrupted I would recommend deleting it and restoring it from a snapshot. If you do not have any snapshot you have likely lost the data and will need to force allocation of the corrupted shard as an empty shard as per the instructions towards the end of these docs.