Azure Pipelines : Terraform Apply fails when given a tfplan - terraform

Question

I'm trying to use Terraform with Azure Pipelines. I use the 0.12.24 version of Terraform.
The steps are the basics :
Install Terraform 0.12.24,
Terraform 'init -reconfigure',
Terraform 'plan -out=$(Agent.TempDirectory)/my.tfplan)',
Terraform 'apply'
Everything goes smoothly until step 4. If I specify the tfplan file ($(Agent.TempDirectory)/my.tfplan), this step fails. If I don't, deployment ends successfully.
Here are the execution trace (generated by TF_LOG = TRACE) :
##[section]Starting: terraform apply
==============================================================================
Task : Terraform CLI
Description : Execute terraform cli commands
Version : 0.5.2
Author : Charles Zipp
Help :
==============================================================================
[command]C:\hostedtoolcache\windows\terraform\0.12.24\x64\terraform.exe version
2020/04/27 16:56:39 [INFO] Terraform version: 0.12.24
2020/04/27 16:56:39 [INFO] Go runtime version: go1.12.13
2020/04/27 16:56:39 [INFO] CLI args: []string{"C:\\hostedtoolcache\\windows\\terraform\\0.12.24\\x64\\terraform.exe", "version"}
2020/04/27 16:56:39 [DEBUG] Attempting to open CLI config file: C:\Users\VssAdministrator\AppData\Roaming\terraform.rc
2020/04/27 16:56:39 [DEBUG] File doesn't exist, but doesn't need to. Ignoring.
2020/04/27 16:56:39 [INFO] CLI command args: []string{"version"}
Terraform v0.12.24
2020/04/27 16:56:39 [DEBUG] checking for provider in "."
2020/04/27 16:56:39 [DEBUG] checking for provider in "C:\\hostedtoolcache\\windows\\terraform\\0.12.24\\x64"
2020/04/27 16:56:39 [DEBUG] checking for provider in ".terraform\\plugins\\windows_amd64"
2020/04/27 16:56:39 [DEBUG] found provider "terraform-provider-azurerm_v2.4.0_x5.exe"
2020/04/27 16:56:39 [DEBUG] found valid plugin: "azurerm", "2.4.0", "D:\\a\\r1\\a\\Build\\drop\\terraform\\.terraform\\plugins\\windows_amd64\\terraform-provider-azurerm_v2.4.0_x5.exe"
+ provider.azurerm v2.4.0
[command]C:\hostedtoolcache\windows\terraform\0.12.24\x64\terraform.exe apply -auto-approve D:\a\_temp/my.tfplan
2020/04/27 16:56:40 [INFO] Terraform version: 0.12.24
2020/04/27 16:56:40 [INFO] Go runtime version: go1.12.13
2020/04/27 16:56:40 [INFO] CLI args: []string{"C:\\hostedtoolcache\\windows\\terraform\\0.12.24\\x64\\terraform.exe", "apply", "-auto-approve", "D:\\a\\_temp/my.tfplan"}
2020/04/27 16:56:40 [DEBUG] Attempting to open CLI config file: C:\Users\VssAdministrator\AppData\Roaming\terraform.rc
2020/04/27 16:56:40 [DEBUG] File doesn't exist, but doesn't need to. Ignoring.
2020/04/27 16:56:40 [INFO] CLI command args: []string{"apply", "-auto-approve", "D:\\a\\_temp/my.tfplan"}
##[error]Terraform command 'apply' failed with exit code '1'.
##[section]Finishing: terraform apply
I've tried this with the two plugins available (the one from MSFT and the other from Charles Zipp).
Any question, input or suggestion is very much welcome.
Thank you for your time :)