We have had multiple issues where a course is "locked" and can't be edited anymore. The culprit has always been javascript that has been copy-pasted along with seemingly innocuous text.
Is there a "paste without formatting" feature built-in in Atto?
Chrome behaves better but sometimes Chrome introduces a lot of garbage even with the "paste as text" (ctlr-chift-v).
We instruct teachers to recycle texts in Notepad, but this seems an overkill especially with short pieces of text that looks like plain text.