Get-activityevents the continuation URL is sometimes going to the wrong address!

I am aware my subject title is quite a statement-let me explain…

The following is a snippet from my code

if (!$result.continuationUri)
{
Add-Content -Path 'debug.txt' -Value ' next activity call '
Add-Content -Path 'debug.txt' -Value $activityAPIUrl
$result = Invoke-PowerBIRestMethod -Url $activityAPIUrl -method Get | ConvertFrom-Json
}
else {
Add-Content -Path 'debug.txt' -Value ' next activity continuation call '
Add-Content -Path 'debug.txt' -Value $result.continuationUri
$result = Invoke-PowerBIRestMethod -Url $result.continuationUri -method Get | ConvertFrom-Json
}

Now when it fails, I have noticed the following:-
firstly it only fields when making the call using the continuation token

Secondly, when it fails, it is calling the wrong URL.

Please note, from the code above, when there is a continuationUri, then this URL is used in the next call.

The original URL used is:-

admin/activityevents?startDateTime=…

The continuationUri, when it works is:-

https://api.powerbi.com/v1.0/myorg/admin/activityevents?continuationToken='LDIwMjMtMDIt…

However, when it fails, the continuationUri is:-

https://wabi-uk-south-b-primary-redirect.analysis.windows.net/v1.0/myorg/admin/activityevents?continuationToken='LDIwMjMtMDIt…

Any idea why the continuationUri is sometimes incorrect?

Thanks