I can't reliably reproduce the problem. It's not always on the 4th photo or only when we upload 26 photos, or anything like that. It's insanely random.
We've been using PhotoPost Pro for more than 3 years now and this hasn't been an issue the entire time. I'm going to go back through our photos and see if I can nail down when this started and how we might have changed our work flow around the same time.
I'll post what I find out. Thank you, Chuck, for helping me with this.