Thank you for your answer, ntozier.
This is what I did:
I paste the code - looks OK(1.jpg)I check with HTML - looks OK (2.jpg) I save - code disappears (3.jpg)I check with HTML - indeed, my pasted txt is gone. (4.jpg)
As far as I see it, the editor internally encodes HTML Entities well but on save something breaks.
What else can I do?