Linked templates-style deployment fails on unexpected "resource not found"

### Issue Details

Hi, we are encountering an issue with a custom ARM template. We know this is the quickstart repo, but as we could not find a better place and we are attaching a minimum non-working example we thought we can start here.

It is about an eventual consistency we guess: we use the linked template styles, and even if a specific component deployment completes successfully Azure complains the underlying resource could not be found. Specifically, it is the virtual network deployment that shows this faulty behavior.

It seems that downgrading the API version from `2020-06-01` to `2019-12-01` solves the issue.

NWE: [non-working-example.zip](https://github.com/Azure/azure-quickstart-templates/files/5615759/non-working-example.zip)

ARM error: provisioning fails with a conflict, the referred resource is not found: [non-working-example-error.txt](https://github.com/Azure/azure-quickstart-templates/files/5615778/non-working-example-error.txt)

### Repro steps (*if necessary, delete otherwise*)
1. Launch the deployment on an empty resource group
2. After the vnet deployment completes the next deployment depending on it fails
3. Checking on the portal shows that the vnet did get created though

cc @Stavroulakis @patrickdehoon @renepingen

Start by unpacking non-working-example.zip and reading non-working-example-error.txt, then reproduce the deployment on an empty resource group. Compare the linked-template behavior with API versions 2020-06-01 and 2019-12-01, focusing on the virtual network deployment and its dependent deployment. Done means the dependent deployment succeeds without the resource-not-found conflict after the VNet completes.

Written by the indexing model from the issue text.