Pink Crystal Armor cannot be placed?

[Tolnorus]

So, I have discovered that I cannot place Pink Crystal Armor. I can place all other blocks (though I have not exhaustively tried to place them all), but I can't place this one. Anywhere. I can't place it singularly or with a larger brush. I can place other types of crystal armor, but not this one. Also, if I attempt to place a block, it still seems to make an entry in the build history because the UNDO button undoes my failed attempt rather than a successful placement that immediately preceded it. This is in Creative mode in v0.200.335. Odd, right? Any ideas? Am I doing something newbish?