Unable to access related records for multi-select lookup via REST API

Unable to access related records for multi-select lookup via REST API

Given I have `foo` and `bar` data fields:
Campaigns.foo - simple lookup field, linking deals module
`Camaigns.bar` - multi-select lookup field, linking deals module

I am not able to retrieve the multi-select one in the records list REST API:
/Campaigns?fields=bar`
... does NOT return bar values
  1. "data": [
  2.         {
  3.            "id": "...",
  4.             ...
  5.         },
  6.        ...
  7. ],

It does work for the simple lookup though
`/Campaigns?fields=foo`

  1. "data": [
  2.         {
  3.           "foo":  {
  4.             "name": "...",
  5.             "id": "..."
  6.            },
  7.            "id": "...",
  8.             ...
  9.         },
  10.        ...
  11. ],

multi-select values are returned only when requesting a single record, i. e.
`/Campaigns/<record_id>`

is this a known limiation? I want to avoid looping over list results for obvious performance reasons.