I've hit this bug a few times today.
Try to edit [[Woodgate, Queensland]]. I want to move the second sentence in the lede para and its citation ( "At the 2011 census, Woodgate had a population of 941, up from 758 recorded at the 2006 census.") to the History section. I select the text and citation and it is highlighted (good). Then I do either Cut from right-click or CTRL-X via keyboard (either way makes no difference) and nothing is deleted (odd?) so I go to click in the History section in preparation to Paste and discover that I can't click there. Any attempt to relocate my cursor in the article just makes the selected text in the lede flash at me. At this stage, pretty much all I can do is exit the editor.
I tried to be creative. Go back into VE and select the sentence as before and then Copy. Click in History and paste. Good that worked. Now back to the lede para to select the sentence I no longer need there (works) and then hit Backspace to delete it (fails). But if I now position my cursor after the content and use Backspace many times I can delete the content lettter by letter (the citation counting as one letter for this purpose).
Initially I thought it might have something to do with the citation at the end of the selected text, but I found I could cut-and-paste selections involving a citation in other parts of the same article. I have looked at the source code of that sentence to see if there was some weird syntax present but it looks as it should.