Thank you for testing that.
I finally figured out what I was doing that was strange, and I completed a fresh build with no errors. I had both pre-built and compiled-from-source versions of Qt 5.10, in directories Qt/5.10.1/clang_64 and Qt/5.10.1/Src, respectively. In my CMake configuration, I ended up with a mix of references to the Qt directories, and so in a few cases, when a Qt library needed to reference another one, it couldn’t find it in the place it was expecting it. This mainly happened with the QtWeb-related libraries. When I made sure that the CMake cache consistently referenced the pre-built Qt in clang_64, everything worked out fine.
Thanks again everyone for your assistance.