Error pulling data from the PowerBI API

Hi

I want to schedule a workflow that appends data to my PowerBI dataset, by first taking the max date in the dataset, and then appending the results for every day after that to my dataset.

I'm currently struggling to read the data in the PowerBI dataset.

I've tried following this guide:

https://powerbi.microsoft.com/en-us/blog/announcing-the-public-preview-of-power-bi-rest-api-support-for-dax-queries/

but that wasn't working for me. What I'm currently trying is this (in PowerShell)

$requestUrl = "https://app.powerbi.com/groups/{Workspace ID}/datasets/{Dataset ID}/executeQueries"

$requestBody = @"
{"queries" : [ {"query" : "MAXX('WaitTimes', 'WaitTimes'[UpdatedDate])"} ] , "serializerSettings" : {"includeNulls": true} }

"@
Connect-PowerBIServiceAccount
$result = Invoke-PowerBIRestMethod -Method Post -Url $requestUrl -Body $requestBody

This code doesn't error, but it is returning a HTML document and not what I need. Does anyone have any advice?

Thanks