I have a yaml pipeline with 2 stages, each one job and multiple steps.
I based my approach on what is documented on this page : https://learn.microsoft.com/en-us/azure/devops/pipelines/process/variables?view=azure-devops&tabs=yaml%2Cbatch#use-outputs-in-a-different-stage

stages:
- stage: ExportSolutionStage
  displayName: 'Export solution to git'
  jobs:
  - template: ../Templates/Jobs/export-solution-job.yml
    parameters:
      SolutionName: ${{parameters.Solution}}  
      ServiceConnectionName: ${{variables.serviceConnectionName}}
      Repo: 'VAB.PowerPlatform.ReleaseSolutions'
      GitUserName: ${{parameters.GitUserName}}
      GitUserEmail: ${{parameters.GitUserEmail}}
      Branch: $(branch)
      PublishCustomizations: ${{parameters.PublishCustomizations}}

- stage: build_stage
  displayName: 'Build solution'
  dependsOn : ExportSolutionStage
  jobs:
  - template: ../Templates/Jobs/build-release-solution-job.yml
    parameters:
      SolutionName: ${{parameters.Solution}}      
      Branch: $(branch)

The underlying template for the job in the first stage is this

jobs:

- deployment: ExportSolutionJob
  timeoutInMinutes: 360
  displayName: 'Export solution'
  environment: ${{parameters.ServiceConnectionName}}

  pool: 
    name: 'Azure Pipelines'
    vmImage: 'windows-latest'
  strategy:
    runOnce:
      deploy:
        steps:

          # Checkout Pipelines
          - template: ../Steps/checkout-pipelines.yml

          - checkout: ${{ parameters.Repo }}
            displayName: 'Checkout Target Branch'

          - template: ../Steps/install-tools.yml

          - template: ../Base/export-solution-base.yml
            parameters:
              SolutionName: ${{parameters.SolutionName}}  
              ServiceConnectionName: ${{parameters.ServiceConnectionName}}
              Repo: ${{parameters.Repo}}
              GitUserName: ${{parameters.GitUserName}}
              GitUserEmail: ${{parameters.GitUserEmail}}
              Branch: ${{parameters.Branch}}
              PublishCustomizations: ${{parameters.PublishCustomizations}}

Included in one of the step templates is this template

# Set Version
  - template:   ../Steps/set-version.yml
    parameters:
      SolutionName: ${{ parameters.SolutionName }}

Which contains this step

steps:
  - task: PowerShell@2
    displayName: 'Get Solution Version and Set as Build'
    name: SolutionVersion
    inputs:
      targetType: 'inline'
      script: |
        
        Write-Host "Fetch current solution version for solution ${{parameters.SolutionName}}"
        ... obscured logic
        $newVersion = $versionToday + $newVersion

        Write-Host "##vso[task.setvariable variable=NewVersion;isOutput=true]$newVersion"        

In the job of the second stage, I try to get that NewVersion variable via this part

variables:
    NewVersion: $[stageDependencies.ExportSolutionStage.ExportSolutionJob.outputs['SolutionVersion.NewVersion']]

However when I run the pipeline, it cannot resolve this variable.

Variables:
  NewVersion:
    Parsing expression: <stageDependencies.ExportSolutionStage.ExportSolutionJob.outputs['SolutionVersion.NewVersion']>
    Evaluating: stageDependencies['ExportSolutionStage']['ExportSolutionJob']['outputs']['SolutionVersion.NewVersion']
    Expanded: Null
    Result: ''

Any help would be greatly appreciated

Regards,
Sven