While not taking any sides regarding your situation, with all due respect you have neglected to mention two very important and relevant details here:
1. What were the mutually agreed terms expressed within your owner / tenant rental agreement regarding a late, renter-initiated cancellation?
2. Is the resort open and completely available for your occupancy and use for the week which you rented from the owner?
There is a very big difference between a tenant being unable to occupy a timeshare due to actual property closure vs. a tenant becoming personally unwilling to travel. Covid is not a surprise phenomenon after being an ongoing issue and growing concern for more than eight months now and this issue (and any related cancellation policy) should be very clearly and specifically addressed within any properly prepared rental agreement.
KC