C-E R word-wrap sometimes doesn't work

Given: the attached file opened in QtC, and the cursor placed at the end of L36.

When: hitting Ctrl-E, R.

Then: nothing happens.

Expected outcome: the last line is wrapped.

I have not found a pattern so far, it just sometimes doesn't work. At least it's not because it's a .qdoc file, since placing the cursor in the paragraph L78..L82 ibid and hitting C-E R works as expected.