The file I imported evidently had some extraneous characters. Also it was imported with no paragraph breaks.
I tried to make corrections to the file and was unable to. The cmnd X didn’t work, the delete (or backspace) key didn’t work. The return key didn’t work.
Unfortunately the paragraph breaks can be a common problem.
To edit a lesson in the new view, open the lesson, click menu on the top left of the page, and click edit. I’m not sure why certain keys did not work for you, as I’ve never encountered this before and I also use a Mac.
Can’t you edit a private lesson or shared? Are you a Premium member?
As far as I know, only Premium members may edit their private lessons.
Only Premium members can edit imported lessons. I see that you upgraded your account now, so you should be able to edit them.