ReferenceInput does not show loader while possible values and reference record are loading

[anjeylink]

What you were expecting:
When using ReferenceInput expect to get LinearProgress instead of empty input (SelectInput or any other valid children) while data is loading.
I manually set delay in dataProvider to 3 seconds, but loader wasn't shown.

What happened instead:
ReferenceInput renders children like data was loaded, but in reality it's still loading.

Steps to reproduce:
Add ReferenceInput in create/edit form. Simulate delay in data provider more than 1 sec.

<ReferenceInput reference="reference" source="source">
    <SelectInput optionText="name" />
</ReferenceInput>

Possible solution
I think problem is in "useReferenceInputController" when it generates "dataStatus.waiting", because finalData is always empty object and "matchingReferences" will be always empty array.

const dataStatus = getDataStatus({
    input,
    matchingReferences: Object.keys(finalData).map(id => finalData[id]),
    referenceRecord,
    translate,
});

Other information:
There was already issue opened
#5731
https://stackoverflow.com/questions/65488613/react-admin-referenceinput-doesnt-show-loading-linearprogress-while-loading?noredirect=1#comment115901905_65488613

CodeSandbox
https://codesandbox.io/s/admiring-monad-uludk?file=/src/dataProvider.js

Environment

• React-admin 3.11.3

no_loader.mp4

[djhi]

Yes, we had a fix which has been reverted in 3.11 because it introduced other issues. We fixed it in 3.12 by giving the loader display responsability to the ReferenceInput children. See #5767