(Seemingly) Random marking and deleting of text

Since upgrading to the latest (non-beta) version of Scrivener (1.9.13.0) yesterday, I have been seeing what seems to be a random occurrence of blocking / marking of text that I have typed which then is inadvertently deleted as I continue to type. Usually this random blocking of text is just a word or a few characters. But I’ve seen whole sentences suddenly blocked and deleted.

I cannot see any pattern to this except that it may be that it is happening when I pause slightly while typing. I do not think this happened prior to this version. It is, of course, not only annoying but also leaves me considering going back to word processing software. I have been a loyal user of Scrivener for a number of years now but find myself worrying that I will lose work and produce manuscripts riddled with inadvertent errors…

Anyone else having this issue? Any suggestions?