That did the trick, thank you! On larger files, I did get a red bar at the top with a warning that said Affinity had stopped working, but the bar went away as soon as Exterminator was done. I'm on board. I'm going to buy and recommend to all the other astro-geeks. Here's a sample of my first image processed in Affinity.
I'm really liking Affinity so far. I'm using it for astrophotography, and I attempted to use Gradient Exterminator, which is a very popular plug-in for post-processing. I pointed affinity to the directory where the 8bf file was stored, but it doesn't show under plug-ins after a restart. I'm running a trial version, but the plug-in button isn't dark. Affinity Photo will be a perfect option for astrophotographers if this can be made to work.