I just accidentally "reset all settings"
and fortunately happened to have a copy of a very recent export that I was able to paste back into Atahualpa. However, I noticed that some things, mostly settings on the header area (logo placement, image file path, etc.), were all gone. I had to recreate it again.
In the previous incarnations of Atahualpa on my other sites, export/import required no tweaking at all—totally seamless. Am I missing something super basic?