Returning array from activity doesn't get serialized properly

[ejizba]

Activity code

param($name)

$output = @()

$output += "test"
$output += "test2"

$output

Orchestrator code

param($Context)

Invoke-DurableActivity -FunctionName 'Hello1' -Input 'Tokyo'

Expected behavior

It should return some sort of array with "test" and "test2". I just tried an old project and I'm seeing:

"output": [
    "test",
    "test2"
  ],

Actual behavior

It's returning some sort of empty arrays

"output": [
    [
      
    ],
    [
      
    ]
  ]