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.
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.