In one case (isopropanol was the fluid) the product was amorphous rather than crystalline, and shining X-rays on it caused it to shrink somewhat. This has to make X-ray crystallographic analysis complicated.
Although ScitechDaily suggests that this might have application in health care, zinc cyanide is not ideal, being poisonous and explosively reactive. But maybe there are some other substances that will do this too.
The 2-fold pressure-induced percentage volume expansion is 50–100 times larger than that previously observed in zeolites due to superhydration or cation migration (100% cf. 0.8–2.5% volume expansion).(35) While the increase in volume may seem surprisingly large, the resulting new phases contain guest-filled pores, such that the overall system volume (solid sample and fluid medium) is reduced. This eliminates inefficiencies in space filling associated with the interpenetrated structure (Zn(CN)2-I).
So it makes sense, but it isn't ordinary.