Can't submit Camunda form with dynamic list (Camunda 7)

[elazzaro]

My Camunda form has a dynamic list (path: FileList) in which each element has 2 fields (a textbox and a select). The next node in the process is a parallel multi-instance that needs to execute for each element in the list.

The payload of the “submit” is

{
   "variables":{
      "Requester": {"value":"jkl;lkjkl;j"},
      "ServiceAgreement":{"value":"Newark ACA 2024"},
      "FileList":{
         "type":"Json",
         "valueInfo":null,
         "value":"[{\"Filepath\":\"jkl;lkjkl\",\"PaperType\":\"heavy cream\"}]"
      }
   }
}

which looks correct.

If I set the Collection of the multi-instance to FileList, I get this error when I submit:

Cannot submit task form d80b328e-543f-11ef-add1-2c58b9bd1290: ENGINE-02025 Variable 'FileList' is not of the expected type 'Collection'.

And if I set the Collection to ${FileList}, I get:

Cannot submit task form 1ecffed3-5402-11ef-add1-2c58b9bd1290: ENGINE-02024 Expression '${FileList}' didn't resolve to type 'Collection'.

From reading other posts here, it seems that “type”:“Json” might be wrong. If that’s it, I’m at a loss, as that’s what the form is generating.

Where should I be looking? Is this a syntax error?