Problem when highlighting a section of text to erase.

So, I will use Ai to rewrite and then insert a paragraph into my text. I then would like to erase the original paragraph as I dont need it now that Ai has rewritten it for me. So, useing my mouse I highlight the paragraph but Sudowrite does not appear to like that and the screen goes blank (yellow and pink) I then need to go out of Sudowrite and re enter and I am back to where I was, no problem. But obviously I need to be able to erase some text.