I don't think this is really a bug. The PROP tool ignores the 'C' at the end, and just sets the type to 101 (FRZW).
Fusionftw:
If i select the property to type and type in 101C, it will set the type materials you use it on to frzw.
"If i select the property to type and type in 101C"
Something's got to glitch out when you set the kind to a temp. Plus type also works in id's. Watr = 2 Dust = 1 Frzw = 101 and so on. I'm not sure why it didn't break with the C there.