We are looking the way to get the list of value for an Option Set from Dynamics 365 and we are trying to extract this value from this URL:
https://{client}.powerappsportals.com/_api/GlobalOptionSetDefinitions(Name='cr754_color')
And we are receiving the following error:
{"error":{"code":"90040120","message":"You don’t have permission to read the OptionSetMetadataBase table."}}

We have already setup this Site Settings in our Portal environment:
WebAPI/enableReadOperationPreview = true
Webapi/OptionSetMetadataBase/enabled = true
Webapi/OptionSetMetadataBase/fields = *

Now we are trying to create a new permission for the table OptionSetMetadaBase, but this table is not in the list.
How can we accomplish without having access to this table? Or is there any way we can select this table from the list?