If a coin is renamed, you will need to rename all your old coins as well in order to achieve the correct cost basis and according profit.
This can be done using the 'Bulk Edit/Delete' button on the 'Transactions' page or by changing them in the trade table on the same page.
Using the bulk function, select 'Overwrite Coins' from the dropdown menu and replace your old coin ticker with the new one.
After that, all values will be displayed again correctly.