I used to work as a major European lowcost airline customer rep and handled Eu261 requests. All disrupted flights were being collected to an excel sheet and let me tell ya, the "Settle" or accept claims category lines always seemed arbitrary. Think 60-80% Deny category on each batch of disrupted flights. Made up and simplified example:
Flightnumber123 - Paris to London - cancelled due ATC disruption --> Decline
Flightnumber124 - Paris to Eindhoven - cancelled due ATC disruption --> Settle
The real kicker: if claims came through a lawyer/solicitor we had to escalate to "Senior Agents" due to "procedural differences", as in the company actually had to pay 80% of time which was an open secret in the office. (but with other shady stuff like waiting for customary UK solicitor's 'Last Request' type of emails to eventually accept the valid claims).
Flightnumber123 - Paris to London - cancelled due ATC disruption --> Decline
Flightnumber124 - Paris to Eindhoven - cancelled due ATC disruption --> Settle
The real kicker: if claims came through a lawyer/solicitor we had to escalate to "Senior Agents" due to "procedural differences", as in the company actually had to pay 80% of time which was an open secret in the office. (but with other shady stuff like waiting for customary UK solicitor's 'Last Request' type of emails to eventually accept the valid claims).