There appears to be an error after transitioning to a new Subscan importer format.

Wallets refuse to sync with absolutely no data imported giving a 404 error.

As a workaround - please add the transactions manually.

Primarily, connect existing transfers to/from other wallets.

Aggregate and add the staking rewards/trades etc., via Koinly UI.

Developers are investigating the issue, a sample dataset was provided already.