8 hours ago, ElsieD said:
Did you cover the potatoes with water?
No. I put them into a small casserole dish that was set atop the trivet. (I had rinsed them before cutting, so there was a very small amount of water clinging to the skins - a trivial contribution of liquid, I think.) The instruction booklet said to add "at least 1 cup of water" for steaming vegetables, so I added 1 cup to the bottom of the stainless steel insert. That was enough to cover the bottom of the insert but not enough to submerge the trivet.
Further information, though you didn't ask: the booklet said to cook the chunks of potato from 7 to 9 minutes with quick release. I split the difference at 8 minutes. For this purpose, using red (waxy) potatoes that would be cooked again later, 7 minutes might have been adequate.
