POST and GET request via Web API. POST request is succesful, but can't perform the GET request

Thanks for you reply, I now understand why the first GET fails.

The reason is that my first POST request triggers the creation of the file.

Once the file is generated, i can perform the GET request to retrieve the file.

That's why on the second attempt, 9 out of 10 times I can get the file.

What I tried is build in a InvokeAfter function with a loop of 10 x 5 seconds (50 seconds in total), and return the status (this is a separate GET request I read in the API documentation yesterday). Once one of the rows returns "success", then the query should proceed with the original GET request to retrieve the file.

Unfortunately I keep getting the status "running", no matter if I say to run it 10 times for 5 seconds or 10 times for 1 second. But when I try the link in my browser, the status is already on "success". It looks like something is going wrong with the InvokeAfter function. My intention is that after i did the POST request, the status gets retrieved after 5 - 10 - 15 until 50 seconds. Once one of these result as "success", I can proceed to download the file.

See code:

let
//POST request
base_url = "https://*****.nl/api/dataviewresult/"&Dataview&"/json?",
extension = "api_key=*****",
url = base_url &extension,
header= [#"Content-Type" = "application/json"],
content1= "{}",
webdata1 = Web.Contents(url, [Headers=header,Content = Text.ToBinary(content1)]),
response1 = Json.Document(webdata1),
contents = response1[contents],
id = contents[id],

// WAITING table
WaitForList = List.Repeat({5}, 10),
#"Converted to Table" = Table.FromList(WaitForList, Splitter.SplitByNothing(), null, null, ExtraValues.Error),

// GET the status 10x after 5 seconds
#"Added Custom" = Table.AddColumn(#"Converted to Table", "Custom", each Function.InvokeAfter(
() => Json.Document(Web.Contents("https://*****/api/dataviewresult/" & Dataview & "/json/" & id & "/status?api_key=*****"))[contents][status],
#duration(0,0,0,[Column1]))),

//Add GET URL to check whether the ID/Dataview ID are correct
#"Added Custom2" = Table.AddColumn(#"Added Custom", "Custom2", each Json.Document(Web.Contents("https://*****/api/dataviewresult/" & Dataview & "/json/" & id & "/status?api_key=*****"))[contents][url]),
#"Changed Type" = Table.TransformColumnTypes(#"Added Custom2",{{"Custom", type text}}),

// wait until the response is COMPLETE, but max 50 secs
WaitForStatus = Table.MatchesAnyRows(#"Changed Type", each [Custom] = "success"),

// download file if WaitForStatus was successful
DownloadFile =
if WaitForStatus then
Json.Document(Web.Contents("https://*****/api/dataviewresult/" & Dataview & "/json/" & id & "?api_key=*****"))
else
null

in
DownloadFile