Azure dev ops cicd yaml variable for appSettings, multi line causing an error

I have an Azure Dev Ops Yaml file for creating an Azure Function, one of the variables is for appSettings which requires a string, so if i put

appSettings: -val1 ${{ variable.foo }} -val2 ${{ variable.bar}}

it works however when i do this

appSettings: |
    -val1 ${{ variable.foo }}
    -val2 ${{ variable.bar}}
    ...add more variables here

I often get errors saying the is a variable which is empty, however when i go back to the all on one line it works, but managing the single line input isn't a great experience.

is there a different way to achieve a multi line approach?

I can reproduce the same issue when pass the application settings (-key value) as multi-line strings to the appSettings field on the task like as yours.

However, if I add an extra whitespace after each line like as below, the task can work fine and the appSettings can be applied to the function app as expected.

  - task: AzureFunctionApp@2
    displayName: 'Deploy Function App'
    inputs:
      connectedServiceNameARM: 'myArmConnection'
      appType: 'functionAppLinux'
      appName: 'myFunctionApp'
      deployToSlotOrASE: true
      resourceGroupName: 'myResourceGroup'
      slotName: 'production'
      package: '$(Build.ArtifactStagingDirectory)/**/*.zip'
      appSettings: |
        -set1 val11 
        -set2 val22 
        -set3 val33 
      deploymentMethod: 'zipDeploy'