on ice

The first sense (“not being used; temporarily unavailable or suspended”) probably refers to the practice of putting food on ice to preserve it.

• "We're putting the new software features on ice until we can fix the existing bugs."
• "Shortly after taking to the ice, the bear broke loose from its leash and went barreling, spinning, slipping, and sliding all around the rink before he was finally restrained and sedated. Needless to say, that act was put on ice."
• "The agency's dry dock project was on ice. Begun as a routine construction job, the project was now also an archaeological site and, ominously, a resting place for an unknown number of human remains."
• "He [Jacques Parizeau] told the press: "We're not saying never, but that project is on ice for quite a while"[…]."
• "But after a public consultation, the three closures were put on ice and the reductions in opening hours revised at many stations [...]."
• "Boss says there's a mole in our organization. Find him and put him on ice."