Azure Functions Docker Deployment Linux workers are not available in resource group
Seems like you can't have linux and windows resources in the same resource group
There is a current limitation in regards to not mixing Windows and Linux apps in the same resource group as well.
https://docs.microsoft.com/en-us/azure/app-service/containers/app-service-linux-intro#limitations
So you're only option at the moment is to create a new resource group for linux resources
It is not possible to create a linux app service plan and a windows app service plan in the same resource group AND in the same location, but you can use the same resource group and deploy both plans in different locations.
Based on a current limitation, for the same resource group you cannot mix Windows and Linux apps in the same region.
https://docs.microsoft.com/en-us/azure/app-service/containers/app-service-linux-intro#limitations
Though I have discovered that the same error can also occur if you have created an app service certificate via the REST api or via terraform (which is also using the REST api) BEFORE creating the linux app service plan. You must create the linux app service plan before creating the certificate in the same location.