'metadata_title' is not a retrievable field

[KurisuDaNoda]

This issue is for a: (mark with an x)

- [x ] bug report -> please search issues before submitting
- [ ] feature request
- [x] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Minimal steps to reproduce

To fully understand cognitive search and indexing I decided I would recreate all of the resource groups and indexes by myself in the Azure portal. I created my index/indexer following the guide, step by step. This created no issues.

I ran the UI locally on my computer and I could open the homepage. When I went into search or tried to search something It would crash and produce the following code.

Any log messages given by the failure

'metadata_title' is not a retrievable field. Only fields marked as retrievable in the index can be used in $select.
Parameter name: $select
Status: 400 (Bad Request)
Content:
{"error":{"code":"","message":"Invalid expression: 'metadata_title' is not a retrievable field. Only fields marked as retrievable in the index can be used in $select.\r\nParameter name: $select"}}

Mention any other details that might be useful

The fix is to make sure that "metadata_title" field in the index set to retrievable. This is missing in the documentation as followed;

In the picture above "metadata_title" is missing. When I created my indexes "metadata_title" was automatically created.