Hmmm. Here's something I hadn't seen in the build log before ...
Warning (115003): Can't generate programming files for your current project because you do not have a valid license for the following IP core or cores.
Warning (115005): Unlicensed IP: "Nios II Processor(6AF7 00A2)
Warning (115004): Unlicensed encrypted design file: "C:/.../synthesis/submodules/first_nios2_system_cpu.v"
Doesn't change anything. But it is a bit more specific -- though inaccurate. Actually, the
.sof file *is* created. I'm just not allowed to use the programmer to configure the device with it.
It's all a bit much, frankly. :'(