You cannot sign a transaction which is not PENDING_SIGNATURE,
and only one transaction at a time can be PENDING_SIGNATURE for a specific <wallet-id, account, asset>.
The rest of transactions will remain in status QUEUED, until either the PENDING_SIGNATURE one is being signed or cancelled/failed.
Currently, you can query the current transactions by status and cancel the currently QUEUED/PENDING_SIGNATURE ones.
sdk.getTransactions({ status: TransactionStatus.PENDING_SIGNATURE })
sdk.getTransactions({ status: TransactionStatus.QUEUED })
...
sdk.cancelTransactionById(tx.id, { ncw: { walletId } });
Then try to create a new transaction and sign it
We will check internally for the cause of this issue.