same thing happened to me, it showed my btc transaction. just change the server to one that is bch. (click network, bottom right, deselect 'select server automatically' then go to server tab and right click on server (with correct height 478562 as of now, i used casharia) and click 'use as server.' then the btc transaction is gone.
I think I am going to do what you said. Thank you very much for the brief explanation.