Yes, it is/was a genuine .zvi. It opened just fine with Axiovision.so it was not corrupt. Everything "read" up-to-date by the FIji update checker. I ultimately deleted Fiji and decided to start over with a fresh install. However, I got distracted and don't know the results yet.
In the meantime, the very same file opens fine with Fiji on my work computer. One of my working hypotheses is that there is something about having had the 3DViewer beta and or java 3D installed at home that may be caucusing issues. This is just a wild, unsubstantiated guess as it is the most "out of stock" thing that was true of my home Fiji install.
I'm not at the "reproducible enough" stage, to file a BioImage Format bug report yet.