I know this sounds crazy, and I hope it because I'm overlooking something, but yesterday when I was researching sunder, things seemed to go bonky.
Facilities that I hadn't built yet disappeared from the "facilities available to build" menu, and all I was left with was the build magic "facility".
Also, Sunder never appeared on my list of learned spells, and all additional unlearned spells disappeared and I was left with nothing remaining to research (My spellbook only has 11 spells in it so far, I assume that there are more than that)
As someone else mentioned before, when an enemy unit is standing in the shard square, I can't attack it. It just destroys the shard at it's leisure.