Azure issue adding VM Scale Set (Flexible Orchestration) as Application Gateway backend pool

Question

Steps to re-create:

1. Create Azure Application Gateway
2. Create Virtual Machine Scale Sets (VMSS) with Flexible Orchestration
3. Navigate to Azure Application Gateway --> Add Backend Pool --> Select VMSS option

But the newly created VMSS doesn't show up in the downdrop

Answer 1

There are two workaround though

Workaround 1:

1. Navigate to Azure Application Gateway --> Add Backend Pool --> Select VM
2. Now select one of the instance from the VMSS
3. After this the new instances created by VMSS will be added automatically

Workaround 2:

1. Navigate to VMSS --> Networking --> Load Balancer
2. Add VMSS as backend pool to Azure Application Gateway
3. Navigate to Azure Application Gateway --> But the backend pool does not show VMSS
4. Manually added new instance to VMSS
5. Navigate to Azure Application Gateway --> This time it shows VMSS and its instances