I have a few tasks now which just run Powershell script text (not calling an external file) and it seems as though for tasks like these, standard output and standard error are not read at all.

Whenever I make calls to [Console]::WriteLine or [Console]::Error.WriteLine, I get nothing in the task log. I would try something like Write-Host, but it seems that isn't implemented yet.

Is there a way of writing to the standard error/output via a powershell task?

To write to standard error output you should use:

write-error "my error!"

But, in the current version, error output is not captured. We will add that for next version. Thank you for the report!

---