The Trip Cancellation benefit is documented here:
https://www.chasebenefits.com/sapphirereserve2
See page 43:
• No benefit will be paid for any Eligible Travel Expense unless a portion of such Eligible Travel Expense has been charged to the Account.
I read this to mean that Sapphire Reserve does not reimburse prepaid expenses charged to other cards, but of course other cards may also have a trip cancellation feature.
Note that there is a new Guide to Benefits as of October 2024:
https://www.chasebenefits.com/sapphirereserve3
That particular line seems to have been removed. However, a stricter one has been added (see page 33):
Coverage is limited to the lesser of the following:
- $10,000 per Covered Traveler
- $20,000 per Trip for all Covered Travelers and
$40,000 per twelve (12) month period per Account
- the actual amount charged to the Covered Card and/or redeemable Rewards used for a covered travel expense