Fetching Reference List via API returns "L" coded data, not "R", confused!

Hi,

Using the Grist API I am fetching my “App Bundle Discounts” table via records: GET("docs/$master_doc/tables/App_Bundle_Discounts/records")

The table contains a column Apps: type=Reference List, Data From Table=ProductNames, Show Column=Name - in the Grist UI this works fine, I click and select multiple items from that table.

The API outputs: Apps as ['L',16,22,20,48,9] but from Module: GristData - Grist Help Center I think this should be ['r','ProductNames',[16,22,20,48,9]] ?

If I update the field to contain ["r","ProductNames", [16,22,20,48,9,52]] for example, I get errors shown in the Grist UI.

PATCH("docs/$master_doc/tables/App_Bundle_Discounts/records", 
{"records": [ {"fields": {"Apps":["r","ProductNames",[<list>]], <other fields>}}]}

Now the field says:
<objtypes.RecordSetStub object at <hexstring>

Hmm, I failed to mention, it was also failing trying to update using ["L",1234] etc… however this morning it is… So I guess my actual question is, why isn’t it an “r” field?