The search/replace was huge, over 15000 files. No it wasn't really /path/ddd, I just wrote that as a dummy path. I was going through 1 change at a time, did not do Replace All or Preview All.
I since broke that huge project into 2 projects and for unknown reasons the sum of the files in the 2 projects is now 2723+986 = 3709 files. I didn't investigate why the file count dropped so much. Future multi search/replace will only use the 2723 files project.