Premiere 24.5 has to re-render every time I open the project - why?

I recently updated to version 24.5 of Premiere and I'm encountering a bug.  I don't know if it's because of the new version or something else, but every time I re-open the project, everything needs to be rendered again.

I'm currently working on a timeline that's more than an hour long, and there are portions of it that have significant effects.  I rendered everything on the timeline for my first cut after I updated, and everything seemed fine, although the clips took several hours to render.  I'm now going back into the project for fine cuts, and every time I've re-opened the project, the bar is red again and I have to re-render the same clips.  This is a big time waster.  Any troubleshooting suggestions, or is there something obvious I'm overlooking?

This is not something I've experienced previously, and my settings haven't changed from the previous version.