Can run GET, but having trouble with POST when sending API from Power Query Online (dataflow)

I am having trouble getting Power Query online to use the search API in Hubspot, and I cannot look at the api request it generates to debug. When I try and do a POST for SEARCH in their API, I get this error:

DataSource.Error: Web.Contents failed to get contents from 'https://api.hubapi.com/crm/v3/objects/tickets/search' (415): Unsupported Media TypeDetailsReason = DataSource.Error
DataSourceKind = Web
DataSourcePath = https://api.hubapi.com/crm/v3/objects/tickets/search
Url = https://api.hubapi.com/crm/v3/objects/tickets/search

(I think the only difference between GET and POST in Power Query is whether it has Content = "" or not?)

My only two guesses are either the body json has a formatting error, or Power BI doesn't support POST.

This works in Postman:

curl --location 'https://api.hubapi.com/crm/v3/objects/tickets/search' \
--header 'Authorization: Bearer ####' \
--header 'Content-Type: application/json' \
--data '{
    "filterGroups": [
        {
            "filters": [
                {
                    "propertyName": "hs_pipeline_stage",
                    "operator": "EQ",
                    "value": "95185931"
                }
            ]
        }
    ]
}'

This works in power BI ( the GET version without search )

let
  Source = Table.FromRecords(Json.Document(Web.Contents(
    "https://api.hubapi.com",
    [
      RelativePath="crm/v3/objects/tickets",
      Headers = [
        Authorization = "Bearer ####",
        #"Conent-Type"="application/json"
        ]
    ]
  ))[results])
in
  Source

But this does not work in Power BI (which I think is identical to the postman version?):

let
  filter = Json.FromValue(
    [
      filterGroups = {
        [
          filters = {
            [
              propertyName = "hs_pipeline_stage",
              operator = "EQ",
              value = "95185931"
            ]
          }
        ]
      }
    ]
  ),
  Source = Table.FromRecords(Json.Document(Web.Contents(
    "https://api.hubapi.com",
    [
      RelativePath="crm/v3/objects/tickets/search",
      Headers = [
        Authorization = "Bearer ####",
        #"Conent-Type"="application/json"
        ],
      Content = filter
    ]
  ))[results])
in
  Source