This same thing has been happening to me for the past year. On my site, it doesn’t happen just when I upgrade. I agree with Frank. Updating 300+ posts on my blog 15 at a time is very time consuming.
Here are some common plugins that frank, jboze and I all have: Askimet and subscribe to comments for jboze and I. Not sure if they are connected.
I could sure use some expertise on this.
Thanks