There's a post on Reddit saying people need to write INVOL cancellation on the form in comments so it won't be treated as voluntary. That's what we have done but also screenshot the full refund message on FAQs and saved both forms. I wrote a sentence on each form saying something like this is an involuntary cancellation for a full refund as advertised as being available to 31 March 2026. I added if seat bookings are also being refunded please send money back to X account which paid for them. Obviously won't know until get refunds but I think if fails with this evidence chargeback via banks might be possible with debit cards and credit card try provider. Hopefully Emirates will refund in full as promised. Someone said there are different departments for voluntary and involuntary.

The Reddit post is on the Emirates forum and called

Emirates refund clarification for flights affected by airspace disruption (28 Feb – 31 Mar)