track changes fails

OSX10.12.3 MacBook Pro, LO 5.3.0.3

Typing along in a shared Writer document, another user has made changes using Word (current revision)–I don’t think that matters but JIC–I’m typing along making further edits, and this happens:

I took this out, but to me, Tanial knows it’s important for her not to
upset Miri, her only real compatriot
so far. That was part of the…

Because I can’t include the change attribute in copypasta, you’ll have to trust me, but this whole sentence was added with change tracking ON. The text in italics is properly marked and recorded as a change, while the portion between is as if it was part of the original document.
Any ideas what I’ve done wrong? This is not the only place it’s happened. Now I’m faced with going through and finding them (!!) and then marking them some other way so my partner can find them, so help is truly appreciated!