If you are seeing access denied error on the Wallets page for any of your wallets then it usually means your API keys are incorrect, missing the right permissions or they have expired.
This can also happen if there is an IP restriction on the API. You need to allow all IP addresses for Koinly to be able to sync through the API (we are working on support for IP restriction).
Click on the Wallet and then on API settings which will open up a popup box similar to the one below.
Look at the error message shown in the box - this error is the one that Koinly is getting from your exchange API, it can usually tell you in more detail what the problem is ex. missing permissions, expired credentials. etc.
Once you know the problem, simply update your API keys (if needed) and hit Save changes. This will trigger a resync of the wallet.