Powershell curl calls fails on the second request - powershell

Question

I am creating a script to call a couple of endpoints in my service.
The calls look like this:
$scheduleResponse=(curl -Method 'POST' -Uri $baseUrl'/scheduletests' `
-Headers #{"Accept"="application/json";"Content-Type"="application/json"} `
-Body $body)
$scheduleContent=ConvertFrom-Json([String]::new($scheduleResponse.Content))
#Error checks here
$testId = [String]::new($scheduleContent.ScheduleTests.TestID)
$getTestResultsBody = '{"TestID":"' + $testId + '"}' #Hard-coding this value works.
$getResponse=(curl -Method 'POST' -Uri $baseUrl'/gettestresults' -Headers #{"Accept"="application/json";"Content-Type"="application/json"} -Body $getTestResultsBody)
My getResponse fails with this error message:
curl : Unable to read data from the transport connection: The
connection was closed. At C:\Development\Services\TESTService\Test
Clients\Caller.ps1:43 char:27 ... etResponse=(curl -Method 'POST'
-Uri $baseUrl'/gettestresults' -Heade ...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CategoryInfo : NotSpecified: (:) [Invoke-WebRequest], IOException
FullyQualifiedErrorId : System.IO.IOException,Microsoft.PowerShell.Commands.InvokeWebRequestCommand
I debugged my service and it is receiving the correct request and sending the correct response back.
If I hard-code testId in the getRequest, the whole script works. So my guess is that it has something to do with reading the test id from the first call.
Any pointers on what could be wrong?