Can’t search two custom fields at same time

I have it set to return results for custom fields.

I can put in a term that is in either custom field and get a result for either.
So I know it’s able to return results for each custom field.

However, when I type them both in the Search Here dialog box it returns no results.

Example:

Custom field 1 color: red
Searching red returns all red posts

Custom field 2 size: small
Searching small returns all small posts

BUT
Searching red small returns No Results for “red small”!