Azure Redis cache premium deployment failure
Solution 1:
My problem here was actually the result of the section on the following page titled:
What are some common misconfiguration issues with Azure Redis Cache and VNets?
https://docs.microsoft.com/en-us/azure/redis-cache/cache-how-to-premium-vnet
The fairly large table of required network settings has to all be exactly right. Mine was too locked down (and opening up this many things has kind of defeated the purpose my organization was after in adding the Redis to a VNET, but that's a whole other topic.)
Solution 2:
Had the same problem. The correct hint is on the page you linked in your answer, but I will outline it here directly for others: "When you deploy Azure Cache for Redis to a Resource Manager virtual network, the cache must be in a dedicated subnet that contains no other resources except for Azure Cache for Redis instances. If you attempt to deploy an Azure Cache for Redis instance to a Resource Manager virtual network subnet that contains other resources, the deployment fails."
I tried it with a subnet where other resources where in. This does not work. Hope that helps.