The remaining coins, if any, might be in other addresses of the OP's wallet. I don't know why the OP assumes all coins are on just one address. This might be, but it's not a very common outcome when a wallet has been in some use in the past. It depends on the history of receive and send transactions with the wallet. The shown screenshots don't allow much to say until the the blockchain has been synced and the wallet's addresses have been rescanned in parallel.
Another thing: Based on the information provided, it seems that there is a discrepancy in the OP's claim regarding the number of addresses in the Receiving addresses tab and the type of wallet shown in the screenshot. The OP states that he only see one address, which would suggest an imported wallet with only one key pair. However, the screenshot provided indicates that it is actually an HD wallet. This does not make sense.