Standard_F4s_v2 shows NotAvailableForSubscription in zones 1 & 3 (West Europe) but zone 2 works

Summary

On a Microsoft Customer Agreement (MCA) subscription, Standard_F4s_v2 is reported as NotAvailableForSubscription (restriction type: Zone) in logical availability zones 1 and 3 in West Europe. Deployments to logical zone 2 succeed. I'd like to understand the root cause — specifically whether this is a capacity restriction, and if so how it can be remediated.

Environment

• Subscription offer: Pay-As-You-Go under a Microsoft Customer Agreement (MCA)
• Region: West Europe
• VM size: Standard_F4s_v2
• Subscription ID: omitted from this public post — happy to share privately if an engineer needs it
• Note: the same symptom appears for Standard_F4s in the same region; details available on request

Diagnostics

1. SKU restriction — az vm list-skus --location westeurope --size Standard_F4s_v2 --all:

reasonCode: NotAvailableForSubscription
type: Zone
restricted logical zones: 1, 3   (location: westeurope)

2. Subscription logical-to-physical zone mapping for West Europe — az account list-locations:

logical 1  ->  physical westeurope-az3
logical 2  ->  physical westeurope-az1
logical 3  ->  physical westeurope-az2

Combining the two outputs, the restriction affects physical zones westeurope-az2 and westeurope-az3 for this subscription. The working zone (logical 2) maps to physical westeurope-az1.

What I've already established

• The identical SKU deploys successfully in logical zone 2 (physical az1) on this same subscription, so this is not a subscription-wide offer/enablement block — it is scoped to specific physical zones.
• The reason code is NotAvailableForSubscription, not QuotaId, and vCPU quota has headroom — so this is not a quota issue.

Questions

1. Is the NotAvailableForSubscription restriction on Fsv2 in physical zones westeurope-az2 and westeurope-az3 capacity-driven for certain subscription?
2. If it is capacity-driven: is it temporary, is there an expected timeframe for it to lift, and is there a process to request allocation in those physical zones for such subscription?
3. If it is not capacity-driven, what is the actual cause, and how do I resolve it?

Thanks in advance for any insight.