frozen hydrogen that don't heat

While trying to make a room to liquify hydrogen, I get a small amount of solid hydrogen, (few µg). I though it will heat up and turn back into liquid or gas. But since it appears, the temperature has never change. O_o

I stayed a long time looking at this panel. The gaseous hrydogen, drywall, radiant pipe and hydro sensor are all temperature above or under -260.9 °C, that constantly change. But these 2 small bit of frozen hydrogen stays at the exact same temperature.

Vesta.sav