The Regulations require that you were living in the UK "in accordance with the Regulations" at the time the divorce became final. In effect this means producing evidence that the EEA spouse was working in the UK at that time.
If you apply and are refused, then you can appeal. If your ex-spouse refuses to provide evidence to support your case, you can apply to the Tribunal for a witness summons (provided you know where they live or can otherwise serve the summons on them) to force them to give witness evidence (i.e. attend the hearing and tell the Tribunal about their work history) and to produce particular documents (for example, payslips, P60s etc.).
I have also tried to get a Tribunal to order the Secretary of State to make enquiries of HMRC (as it was implied in the case of
Amos that this might be worth a punt) but I have to say the request was basically laughed off!
Think also about what oral evidence you might be able to provide if you know that your ex is actually working. Credible witness evidence from you may also persuade a Judge that your ex was exercising treaty rights.